# PLEASE Read Before Making Homemade H2SO4 pH Down! Important Info You NEED To Know!



## snaxforgandhi

*THIS IS MEANT AS A COMPANION POST TO TATER'S EXCELLENT "Make Your Own pH Down For Pennies!"* POST. IT INVOLVES PROCURING SULFURIC ACID FROM AUTO PARTS STORES AND IS A POSSIBLE SAFETY ISSUE*. *URL="http://www.marijuanapassion.com/forum/showthread.php?t=37804



*{{{READ THIS FIRST!!! Added 10/18/2009 @ 01:59: Hey, something wasn't sitting right with me after I wrote this post, kept nagging at me. I took a closer look at Tater's formula - and I'm really sorry Tater, not trying to be a jerk - but it's wrong*. I'm assuming that he got his figures from a well known recipe because his numbers were exactly the same; 50ml of sulfuric solution to 950ml of distilled water = a ratio of 1:19 H2SO4 solution to H2O and has been the standard formula for a common sulfuric acid based homemade hydroponics pH down for ever. He was right on the money there. Where he went sideways was his assumption that the concentration of the sulfuric acid solution to be mixed was what he called "pure" H2SO4, which would actually be "concentrated" as I have already layed out in the following post. However, this formula actually assumes that you're starting with 33% solution. If you mix this formula using concentrated 97% H2SO4 you will end up with a nearly 5% solution. This is more than twice the intended concentration for this formula, which will result in a 1.65% solution if 33% H2SO4 is used. This may seem like a small difference, but due to the exponential nature of ionic dispersion (H+) in a non-buffered solution it'll pack a wayyyy bigger punch! It'll work but it's much more touchy and at 5% it's also much more hazardous to handle. Think of it like this: The area of a 9 inch circle is more than twice the area of a 6 inch circle, even though it's only 1/3 larger in diameter. There's nowhere near enuf room to explain all this, just trust me. Sulfuric is what is known as a strong acid, meaning dispersion of hydrogen ions (H+) in solution is 100%, and as H2SO4 gives up 2 protons to HCI's 1, it has twice the molarity per given mass, and makes for a touchier solution that's more sensitive to little changes than most commercial solutions. 

Here's the simple version: 
Mix 50ml of 33% sulfuric solution (read this post to learn how to determine what you bought) to 950ml of distilled water for 1 liter of a 1.65% pH down solution (50x0.33=16.5=10^3x0.0165=1.65%) 

or, 

Mix 70ml of 33% solution to 890ml of distilled water for 1 U.S. quart of 2.4% solution (70x0.33=23.1=960x0.024=2.4%). 

To use the 1.65% solution mix approx. 5ml(1tsp)/liter for a drop of 1 pH point, and to use the 2.4% mix approx. 15ml(1Tbs)/gal. for a drop of 1 pH point. THIS IS APPROXIMATE and to a greater extent than commercial pH down will depend on the TDS/EC and degree to which your water source/nutrient solution is naturally buffered (remember, everything is a bit touchier with a sufuric pH down) You'll have to experiment to find the perfect ratio for you, and though sufuric acid solutions are a little more sensitive, it's totally worth it for how much $$$ you can save. Tater was right on the money there!

All I have corrected is Tater's numbers in relation to the molarity of the sulfuric acid source. Please follow everything else he says in terms of mix order, caution, etc.. Read on to learn how to know what you're buying so you can start with the right stuff. Love peeps!  }}} * 




			
				Tater said:
			
		

> ...A jug of sulfuric acid (also known as battery acid)...


 


			
				Tater said:
			
		

> .... 5 bucks got me 1.5 liters of pure sulfuric acid....


 
*Greeting Earthlings! *

Fairly new to the forum, but I've been producing pH up/down for years (among other interesting forays into organic chemistry). First: I got nothin' but love for Tater!! I'm totally, unequivocally and thoroughly onboard with your independent initiative Tater. Believe that. Also, I have zero use for the "You'll put your eye out!" crowd myself. (I'm a big boy and they even let me use the grown-up knives at dinner!) 

I offer the following humbly and purely in the spirit and belief that knowledge is the greatest tool and most powerful weapon in the world. We are all capable of many things (including handling strong acids and bases) but we _need_ solid instruction. 

*All I want to do is clear up a couple things.*

1. YES!! Sulfuric acid makes a dynamite down agent and you can totally make your own at home! BUT, your statement that sulfuric acid is commonly known as "battery acid" isn't quite accurate - at least as far as auto parts stores go - and could be, at the least, a practical problem and, at worst, a safety issue. The culprit here is confusion and I want to avoid it is all.

So...

*Not So Important...*
Some automotive and motorcycle parts stores do indeed sell _concentrated _sulphuric acid (calling it "battery" acid 'cuz that what it's used for in this industry), which is generally 97% or 98% pure. However, 100% "pure" H2SO4 is not sold because sulfuric acid loses sulfur trioxide (SO3) at boiling point, reducing concentration to a little better than 98%. So, the words _pure_ and _concentrated_ mean specific things in chemistry, and it can REALLY matter sometimes.

*Much More Important...*
Automotive and motorcycle parts houses also carry a product called "battery acid," or "battery fluid," which is a _premixed_ - and sometimes buffered - solution of 33% (4.2 molar) sulpfuric acid in solution with distilled water. Also, it has been my experience that a parts store will carry either one (97%) or the other (33%), but not both. *NOTE: 99% OF THE PEOPLE WHO WORK AT THESE STORES DON'T KNOW THE DIFFERENCE AND IT ISN'T USUALLY REFERENCED ON THE PACKAGING!!! *

Both the concentrated and premixed come in boxes with the big scary NFA panel and huge warnings with pictograms showing acid burns to human flesh and reactive metals. Neither typically indicate the concentration anywhere on the packaging. Figures 1-5 are examples of both concentrated 97% sulfuric and premixed 33% solution. Can you tell the difference?

The reason this is important is because the 1st post in this thread is calling out _specific_ ratios (50ml H2SO4/950ml distilled water) that assume a _concentrated_ sulfuric acid component of 97% purity. **((THESE NUMBERS ARE WRONG! READ ADDENDUM ABOVE!!))* Obviously it will not produce the same final product if what you're calling concentrated acid is, in fact, only 33% pure. Conversely, if you bought 33% solution one time, mixed it until it worked, then got some "battery" acid at another store and it turned out to be 97% and you mix it to the same ratios you're gonna totally zap your 'nutes and/or roots, and just might fry your hands in the process. 

*HOW TO TELL THE DIFFERENCE SINCE RETAIL CONTAINERS RARELY SPECIFY CONCENTRATION:* First, don't ask the counter help; often people will answer questions that they are not qualified to answer in an effort to be helpful. This is especially true of retail clerks whose job it is to "help" the customer. It's well-meant but not very reliable. 

So here's the deal: _Concentrated_ sulfuric will have instructions in the box on how to create a solution by mixing with distilled water. _Premixed_ "battery acid/fluid" will instruct the customer to add it as-is to the battery cells. 

So...
One is *"battery"* acid, meaning: "Acid that is to be mixed with water and _then_ added to a lead/acid battery," 
The other is *"battery acid/fluid," *meaning: "The _already mixed_ stuff that is ready to go into your battery right out of the bottle/pouch/bag." 

Again, I only mention any of this 'cuz I want everyone to have success and safety in all their growing endeavors, and that's what MP is all about, right? Love peeps!

~Snax (He Who Lurks)


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## Hick

snax... I added this to the sticky AND edited the photobucket links once...
please, don't link to outside image hosts. Use our server ..


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## snaxforgandhi

Hey Hick!

Dude, I missed your first edit _completely! _I was like, "Why is this post acting so screwy?' I just kept fixin' it! Sorry man, I'm kinda baked. I swear I was _not_ trying to be all obstinate!  

Anyway, what's a "sticky?" I'm the lowliest of newbs and a bear of small brain, and long words bother me...

~Snax is humble... Snax is good...


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## Tater

Hey thanks for the great post, I wasn't aware of that and I never really gave it much thought to be honest.  The sulfuric acid I sourced was concentrated then and was meant to be diluted before being added to a battery.  I did however not have any problems at the dilution ratio I stated although it was quite hot and had to be used carefully, I find it comparable to AN's down as it is also on the "hot" side.

Great post and don't worry about stepping on my toes brother I keep em in steel toed work boots haha.  Very good info.


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## Tater

Added a link at the beginning of my post to this thread, hope you don't mind.


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## IRISH

yeah snax. thanks for the useful post. that would make a bit of a difference. good looking out brother...

a sticky is a thread that is enshrined at the top of the section your posting in for all to view every time they enter this page. ...

got any snax?  ...


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## snaxforgandhi

Tater said:
			
		

> ...don't worry about stepping on my toes brother I keep em in steel toed work boots haha.


Man, I'm glad that you weren't offended. I would have hated that. I should have known you probably wouldn't be though since everyone at MP has been nothin' but cool since I joined. And again, I love your independent "DIY" streak! I'm exactly the same way!



			
				Tater said:
			
		

> Added a link at the beginning of my post to this thread, hope you don't mind.


Nah man, do it up! I added a link to yours! 



			
				Irish said:
			
		

> a sticky is a thread that is enshrined at the top of the section your posting in for all to view every time they enter this page. ...


Ahhhh, I see. But now I'm confused... my post isn't a sticky, is it? No matter, I kinda like being a bit confused at times! 

~Snax (He Who Lurks)


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## PUFF MONKEY

now all you need is some nitric acid with a specific gravity of 1.84 and some glycerine....lol


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## snaxforgandhi

PUFF MONKEY said:
			
		

> now all you need is some nitric acid with a specific gravity of 1.84 and some glycerine....lol


*I don't get it. I'm mixing them together... is something supposed to hap-BOOOOOOOMMM!!!!!!!!!!!!*

~Snax (He Who Rests In Pieces)


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## Tater

No no you're doing it all wrong you need to shake it really hard.


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## DonJones

Both Tater and Snax have great points -- but to make it a lot simpler here is what I did before Snax found and updated Taters post.

I went to my local commercial battery supplier (and auto parts store will do just as good) and bought a quart of "battery acid" which was actually the premixed fluid (I haven't seen any battery store or auto parts store handling the concentrated for a long time for both safety and ease of use by the customer).  I brought it home and mixed it by adding 1 part acid TO *8.5 *parts of the water --*ALWAYS ADD ACID TO WATER BECAUSE IF YOU GO THE OTHER WAY IT MAY BOIL OVER, SOMETIME ALMOST TO THE POINT OF APPEARING TO EXPLODE* --letting it sit for a while to start mixing and then gently agitating it to finish mixing.  *CAUTION EVEN AT THIS DILUTED STRENGTH IT IS CAPABLE OF CAUSING SERIOUS INJURY TO THE EYES OR IF INGESTED.  CLEARLY LABEL IT AS POISON AND KEEP IT STORE PROPERLY.*

Then I filled several jugs with tap water, let it sit to remove as much chlorine as possible, and began adding the PH down a little bit at a time until i got it down to the point I was looking for -- I use 6.0 -- and then I added that same amount to several of the jugs to confirm that I had it right.  ( I found that adding a little at a time yielded different results than adding it all at once and I don't know why).  Then I labeled my PH down bottle with the amount that I needed to add per gallon.  Now all I do is add that amount to each gallon that I use and randomly check a gallon of each batch ot make sure that my tap water PH hasn't changed (which is real unlikely since it is on a city water system) and go about my business.

In my case I started with the premixed fluid, diluted it 1 part acid to *8.5 parts* tap water, and add 1.3 ml of the resulting solution to 1 gallon of my tap water and it hits 6.0 + or - 0.1 every time starting with tap water that is 7.0.

The same procedure will work regardless of your water's starting PH, although the final amount needed to adjust your tap water will vary with the starting PH and your desired ending PH, but the same is true of any PH adjuster.

I chose *1 part acid to 8.5 parts water (100 ml of premixed 33% battery fluid, acid)* [Edited by DonJones to correct error in ratios.]  just to be safe giving me a 3.48%  solution, if I didn't screw up the math, which is getting pretty hot.  I'd recommend either the 2.4% or the 1.65% solutions that are listed in Sanx's post above! The actual ratio is not critical BUT THE MORE DILUTE YOU MAKE YOUR PH ADJUSTER, THE LESS DANGEROUS IT IS TO STORE AND HANDLE -- ALSO, A SLIGHT ERROR IN MEASURING HOW MUCH YOU ARE ADDING WILl NOT CAUSE THE END PRODUCT TO VARY AS MUCH.

Also remember that adding too little and having to add more is safer than adding too much and having to try reverse that process with another additive.  At any where near the ratios that I use, the diluted solution and the PHed water can both be disposed of safely by running water down the drain while you are slowly pouring in what yo9u are disposing of.  I have even just dumped it out on the lawn and then watered the lawn thoroughly.

I do NOT disagree with anything TATER or SNAX have said, I'm just adding an other approach.

Good luck.

Incidentally the same procedure will work with either sulfur, phosphorous, or potassium based acids.  The slight amount of the base element added over all SHOULD not effect your plants, but if you are worried about sulfur problems you can try the others.  However the others aren't as easy to find in my experience of as inexpensive.  If this all seems to complicated or dangerous to you, then by all means buy your PH adjusters premade but *remember any PH adjuster will be dangerous to your eyes or if ingested.*


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## PUFF MONKEY

snaxforgandhi said:
			
		

> *I don't get it. I'm mixing them together... is something supposed to hap-BOOOOOOOMMM!!!!!!!!!!!!*
> 
> ~Snax (He Who Rests In Pieces)


chemistry was always a favorite of mine


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## snaxforgandhi

Hey Earthlings! Me again...

I wasn't going to respond to this post initially, but *YIKES!* It drove me nutz all night last night. It's a safety thing and, though I am loathe to step on anyone's tail, if I have to choose between safety and tails I will choose safety every time. But, I'll be as gentle as I possibly can. 

First, let me say "Howdy!" to DonJones. I am glad to see that folks are reading this thread! And thanx for your input! Everybody's got a voice at MP!

I must confess, however, to being somewhat puzzled - and a little bit alarmed - after reading your post. I'd like to reiterate that these were the same reasons I initially responded to brother Tater's fine post.



			
				DonJones said:
			
		

> Both Tater and Snax have great points -- but to make it a lot simpler here is what I did...


It is entirely possible that I missed your meaning (for I am a bear of little brain sometimes  ), but Tater's original post - and my response - both dealt with buying acid at an auto parts store and mixing it with water to make pH down. This seems to be exactly what you describe as well. Again, maybe I'm missin' it.  



			
				DonJones said:
			
		

> ... _bought a quart of "battery acid" which was actually the premixed fluid (I haven't seen any battery store or auto parts store handling the concentrated for a long time..._


_:holysheep:_ I just bought one and half liters of 97% non-reagent grade sulfuric acid at a nationally recognized auto parts house. Further, I believe that Tater stated that his, too, was indeed concentrated sulfuric. It alarms me to hear someone asserting that high-mole sulfuric is simply not sold because it suggests that folks can just assume that they're getting the weaker 33.53% solution wherever, and whenever, they find it.

This is simply _not_ true and reinforces erring on the wrong side of safety. If we're going to assume anything, let's play it safe and assume that our concentration is the _higher _ (96%-98%) until we know otherwise. I liken this to assuming a gun _isn't_ loaded. All guns should be assumed to be loaded until we _know_ otherwise. Don't take chances when you're dealing with a strong acid or base.

Folks, please follow the guidelines I layed out for determining the concentration of your purchase, and _never, ever_ assume it's the weaker solution. 



			
				DonJones said:
			
		

> In my case I started with the premixed fluid, diluted it 1 part acid to 3 parts tap water...


*YIKES!! *Again, nothin but love DJ (I _really_ mean that!  ), but I have to respectfully submit that this is just _not_ a good idea, for a number of reasons:

1. Tap water is loaded with impurities, mostly mineral (some organic), that react with H2SO4, with some reactions being very energetic.

IMPORTANT FOR PLANTS... Not so important for peeps
*(a) *Many of the impurities in tap water are solute bases. Higher concentrations of sulfuric acid (including 33.53% premixed battery fluid) react with most bases in aqueous solution resulting in that base's corresponding sulfates being suspended in solution. This isn't good 'cuz sulfates can just play havoc on your nutes. 

*(b)* Like solute bases, many of the impurities in tap water are transition (and other) metals. Again, sulfuric will react with most metals, producing _their_ corresponding sulfates, plus hydrogen gas, which are then suspended in solution. Also, some metal nitrates, like potassium nitrate, react with sulfuric acid to form nasty precipitates that not only mess with your PPM/EC in a big way, but they also cloud up your nutes and can block oxygen uptake in your roots. One of the biggest worries here is Copper Sulfate and the extreme level of phytotoxicity in plants. It kills plants dead by disrupting photosynthesis. Someone's gonna say "But Snax, isn't copper sulfate used as an antifungal?" The answer is yes... on _foliage_, and even then it's a crapshoot. It's poison, poison, poison to roots, and that's where our nutes go, yes?

Neither bases nor metals, or their respective sulfates and precipitates, are much of a problem if you dilute sulfuric acid in ionically neutral _distilled_ water first, and _then_ add it to your nutes. _In this way_ the sulfuric acid - after 100% ionic dissociation - is in low enough concentration that reaction with weak bases is greatly diminished due to the inability to displace the the hydrogen anion. 

So.... strong acid added to tap water, then added to nutes = bad. Strong acid added to distilled water, then added to nutes = good.

IMPORTANT FOR PEEPS!!!
2. Another reason to avoid mixing high concentration sulfuric acid with tap water is that if there is even a trace of colloidal copper in your tap (highly likely considering that most modern plumbing is copper pipe), the action will produce sulphur dioxide, a _highly_ toxic gas that, even at low concentrations, is a severe respiratory irritant, and in the long term will significantly damage your lungs and liver. 

We tend to think that if we survive the handling of sulfuric acid without it exploding in our face, or eating a hole in our flesh, that we've successfully avoided danger. WRONG! The EPA has set a maximum safe exposure to sulphur dioxide at 0.03ppm in air! If you can detect 0.03ppm by breathing it then you're a better man than I. Oh, and by the way, these effects are about 5-fold in children. So, just 'cuz you mixed something up and it brought down your nute's pH without killing you, doesn't mean what you did was safe. 

You can't just "wing it" with strong acids, folks. We (growers) continuously work with these chemicals, exposing ourselves month after month, year after year, and must _educate_ ourselves as to proper handling procedures to avoid hurting our plants, ourselves, and especially those around us, particularly our children!

*Continued Below.......................*


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## snaxforgandhi

*Continued From Above.................*


			
				DonJones said:
			
		

> I found that adding a little at a time yielded different results than adding it all at once and I don't know why...


I can actually help you out here DJ  ; Again, tap water is brimming with impurities and, as I mentioned, some of it is organic material: plant proteins from roots in water mains is a big source for this. These impurities - mineral and organic - tend to act as an "accidental" buffer agents and act to resist changes in pH: Buffering occurs in an aqeous solution when there are present a weak acid(s) and its conjugate base in equalibrium. pH stability - or stasis - is achieved by the consumption of added reagent - in this case H2SO4 - as the equalibrium expression of the buffer agents shifts to accomodate the addition of Hydrogen cations. Negatively charged proteins add to this effect. In essence, some of the acid gets used up as the buffering agents attempt to maintain equalibrium, so the pH doesn't change nearly as much as it would in an unbuffered solution, like distilled water. This is oversimplifying, but basically the reason that you're getting different results by adding acid slowly or all at once is that it takes time for this buffering action to occur, and going all at once simply overwhelms the buffer: e.g., _rate of introduction affects linearity of ionic dissociation_. NOTE: This does not happen in distilled water as there are no buffer agents, and ionic dissociation (H+) is immediate and linear.



			
				DonJones said:
			
		

> I chose 1 part acid to 3 parts water just to be safe -- the actual ratio is not critical...


Again, wow. First, DJ, your ratio of 1 to 3, "just to be safe", is anything but, assuming you meant "safe to handle." I know this all sounds harsh, but I don't know how else to put it. Let's take a look at the math and chemistry (and, IMHO, anyone who thinks this is too much trouble or unneccesary has zero business handling strong acids): 

We'll start with your pre-mixed battery fluid. The current industry standards are not exact, but the generally agreed upon molarity of wet-cell lead-acid battery electrolyte is around 4.2M to 4.4M, yielded by a 33%-34%w/v concentration (they shoot for 33.53%). So, knowing our molarity, and knowing that the molecular weight of H2SO4 is 98.08g/mol (trust me; it is), we calculate equivalent mass in your quart:
4.4M x 98.08g/mol x 1L = 431.55g H2SO4​So, there's the equivalent mass of 431.55 grams of sulfuric acid solute in a liter of this stuff, so correcting for imperial measures we get 408.42 grams (431.55g x 0.9464) per quart. Now we need to figure out what we'd end up with if that same 408.42 grams was dissolved in 4 quarts of water instead of one, or a 1:3 ratio. 
(431.55g / 4L) / 98.08g/mol = 1.1M
or
(408.42g / 4qt) / 98.08g/mol = 1.1M​Now we have a 1.1M solution, or a roughly 10%w/v concentration. This is the _exact_ dilution found in chem labs all over the world; you know, the ones where they wear big rubber gloves and goggles so as not to burn the bejeezits out'a themselves. Here's an exerpt from the MSDS on 10% reagent grade sulfuric acid:
DANGER! CORROSIVE. *LIQUID AND MIST CAUSE SEVERE BURNS TO ALL BODY TISSUE*. MAY BE FATAL IF SWALLOWED OR CONTACTED WITH SKIN. HARMFUL IF INHALED. AFFECTS TEETH. CANCER HAZARD. STRONG INORGANIC ACID MISTS CONTAINING SULFURIC ACID CAN CAUSE CANCER. 
Health Rating: 3 - Severe (Cancer Causing)
Contact Rating: 4 - Extreme (Corrosive)​Scary Monsters, huh? Here's a link to the full MSDS sheet if anyone needs futher convincing: (Remember to change the "hXXp" to "http" in the link or it won't work)hXXp://www.jtbaker.com/msds/englishhtml/s8236.htm

At this concentration you are _beggin'_ for an exothermic reaction, made all the more energetic by the cocktail we like to call "nutrients!" That's not a fun shower folks, I speak from experience. There's a reason that the commercially available pH down is nowhere near this hot. It's just not safe to handle under any but laboratory conditions. Even then it's not exactly "safe," it's just that they have the gear to do it right. I don't think many of us here at MP glove, goggle & gown up to add a little pH down, and who wants to?
Please guys, follow the ratios listed at the top of this thread and stay safe!!

*DonJones, I truly apologize in advance if I've stepped on your toes; it is absolutely not my intent. You were very kind to Tater & I in your post and I truly applaud the spirit of helping and providing alternatives for folks. I really mean that. It is the thing that I love about the internet in general, and MP in specific. I simply see this as a safety issue and I cannot, in good conscience, ignore it. I wish you and yours all the best in your MJ endeavors, and continued safe growing!!*

Love Peeps!
~Snax (He Who Lurks)


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## Tater

Snax you are a wealth of information.  Thanks again for taking us all to school.


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## snaxforgandhi

Tater said:
			
		

> Snax you are a wealth of information. Thanks again for taking us all to school.


It is my _Honor_ and my _Pleasure_ to offer whatever humble service I can, particularly if it might help someone avoid a dangerous situation. It is the least I can do in exchange for the invaluable education I am receiving from all of you gurus here at MP! Thank you, Tater, for the affirmation; I really worry that I'm gonna upset or offend someone with these posts, and getting positive feedback goes a long way to alleviating that stress. Snax thanx you Brother!


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## Tater

Haha, man don't worry about stepping on toes so long as you aren't going out of your way to be mean to someone then its not your fault if they take offense.  What most people get upset about is nothing more than a bruised ego and not any real slight.  

Personally I've found your posts very enlightening and I wish I had more time to dedicate to learning chemistry but it is definitely on my life long list of things to do.  High five brother, keep spreading the good word!


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## DonJones

snax,

No, you didn't step on my toes, you just thought it through further than I did and I didn't clarify my point well enough, which was just find a dilution that you are comfortable with and then experiment with your water, what ever kind you are using, and until you know how much to add to each gallon and have the PH hit where you want it.  Then record that amount as well as your formula for your PH down.  I did NOT mean to suggest that my dilution ratio of 1 part acid to 3 parts acid was a good ratio, just an example of how I did it.   I PH my water first and then add the nutes because the nutes are already near the ideal PH for that formula and the amount I add is very small and should not change the PH significantly.  Also, since I'm using visual reagents to check the PH any thing that changes the color of the solution makes PHing after adding it to the PHed water pretty unreliable.  

However I didn't say the concentrated acid was NOT available in auto parts stores, just that I hadn't seen if in  along time.


We agree on more than we disagree on.

We agree that handling any kind of acid at any concentration is NEVER SAFE -- it just gets less hazardous as the acid is further diluted to weaker and weaker concentrations.  Even vinegar is hazardous if mishandled.

As to the hazardousness of 10% of approximately 1 molar sulfuric acid, when I took chemistry the last time in college, including biochem, as well as in high school we never wore gloves or aprons to handle 1 mole sulfuric acid.  

However we had been trained very thoroughly on handling it and we did NOT stand over the beaker when adding any acid nor breathe the fumes.

We agree 10% is very hot for a PH down and MUST BE HANDLED WITH CARE AND RESPECT.  We also agree that closer to 1% would be safer than the 10% that I use.

I may very well change my dilution ratio to nearer to the 2.4% you mentioned.

*Once again for your own safety always add acid to the solution.  Always treat every chemical that we use as very hazardous.  That way any accidental contact with the chemical will probably be very minute and not too harmful.  Remember the smaller amount of a chemical that they tell you to use to reach the strength they tell you to dilute to, the stronger that chemical is and the more carefully it needs to be handle and the prescribed formulas followed. *


Respect every chemical, even the organic ones ( one of the most toxic poisons known to man is found in the castor bean and when extracted is almost always fatal if introduced into the blood stream), and treat it with care or you will eventually do harm to someone or some thing!


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## snaxforgandhi

DonJones said:
			
		

> ...No, you didn't step on my toes...


I'm relieved to hear that. Written communication - like forum chat - completely removes the "face" factor from the equation, and so it becomes all the more difficult to communicate the subtle difference between, "You're wrong dummy!" and, "I disagree, but it's not personal." I always worry that I'm coming off like the former. Glad to hear no feathers were ruffled!  



			
				DonJones said:
			
		

> ...I PH my water first and then add the nutes...


I did this too, for years in fact. This because of my "chemist first, grower second" mindset. Sounds like you know a bit about chemistry so you'd probably see it the same way I did, which was to take the logarithmic nature of the pH scale into account and simplify the reactive potential of adding dissolved solids to water by adjusting pH to match the solids before adding them. Makes perfect sense.

However, the last time I went to 'dam I stayed with a guy and his girlfriend for about a week - both major pothead/growers  - and I gotta tell ya, his non-chemist butt changed my mind (much to my inner-chemist's chagrin, dang it!). He argued that almost all commercially prepared nutirents are buffered (and as far as I've been able to discern he's right) and it's both a waste of pH bumper _and_ can make for more unwanted precipitates in solution to adjust water first. This because a buffered nutient added to water will take care of a significant portion of any needed pH adjustment by means of it's own weak acid/conjugate base component without changing the original composition of the nutrient overly. Any remaining necessary adjustment is then taken care of with a smaller amount of bumper than it would've taken to adjust the water first. Then he proved it (dang it!). 

I had to admit that he was right, then I got even by smoking oodles of his pot before I left. I showed him. Anyway, I adjust _after_ these days, though I understand and respect that many make a good arguement not to.



			
				DonJones said:
			
		

> ...Also, since I'm using visual reagents to check the PH any thing that changes the color of the solution makes PHing after adding it to the PHed water pretty unreliable...


I can dig it! I'm in the same boat right now. I broke the membrane of my digital - 'cuz I'm a genius - and I've been using a pHast visual reagent kit for a couple of months. I agree that any colorant makes it difficult to be certain of the results. One way around that is to use a very narrow range reagent kit (mine's 5.2 - 6.7) with a large color disparity (mine goes from a vibrant yellow to a deep purple in only six gradient steps). That way it makes it easier to visually factor out any color weirdness. My nutes tend to color the solution kinduv reddish-brown, so if my reagnet looks a bit orange-y, it's toward the yellow end of the range (low), whereas a more fuschia-y color indicates a trend toward the purple end of things. Again, with such a narrow range, and with 6.1 being dead center and indicated by a neutral gray color, any color either way is easy to interpret and any error is in tenths of a point, not whole points. This all being said, I MISS MY DIGITAL METER! I just need to bite the bullet and buy a new pH 'trode for it. 



			
				DonJones said:
			
		

> ...We agree on more than we disagree on...


I agree that we agree on more than we disagree on, so we can agree that we are in agreement as to the degree to which we agree or disagree. Do you agree?



			
				DonJones said:
			
		

> ...As to the hazardousness of 10% of approximately 1 molar sulfuric acid, when I took chemistry the last time in college, including biochem, as well as in high school we never wore gloves or aprons to handle 1 mole sulfuric acid...However we had been trained very thoroughly on handling it and we did NOT stand over the beaker when adding any acid nor breathe the fumes...


Right, this was my point. The folks who are gonna read these posts and attempt the procedures therein are gonna mostly be stoners, alone in their basements with no eyewash stations or acid/base nuetralizer bottles. Seems the safer we can make it the better.



			
				DonJones said:
			
		

> ...Even vinegar is hazardous if mishandled...


Too true! I once mixed some oil & vinegar salad dressing and oversported on the latter... totally ruined my salad!  

Thanx for being evolved and openminded DonJones, truly. It is, unfortunately, becoming more and more difficult to find folks whose egos aren't so fragile that they melt down at the slightest debate. (and if you disagree with that I'm gonna throw a huge coniption fit!!  ) It's been a pleasure!

~Snax (He Who Lurks)


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## DonJones

Snax,

Another reason I work with the water first is I am color vision impaired-- not color blind but impaired and my reagent goes from blue through green to a very pale yellow.  Of course the color difficency (sic) is red-green.

I have PHed my water to 6.0 added the nutes and had samples We are using 2 different nute mixes) checked at a local hydro store and it stayed within 0.1 of where I started.

I try to be glad when some one catches something that I post as being potentially harmful to someone reading it without the background/mind set that I have, but sometimes it is hard to not read more into it thanthe poster means.


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## snaxforgandhi

DJ,

Yeah, I suppose being color impaired would have a pretty whoppin' effect on trying to read a colored reagent test! And red-green to boot! Have you thought about using a digital! I love mine, when I haven't broken them of course . My better one (the one I broke) also reads TDS/EC, and compensates for temp. It totally spoiled me. I miss it big time. 




			
				DonJones said:
			
		

> I try to be glad when some one catches something that I post as being potentially harmful to someone reading it without the background/mind set that I have, but sometimes it is hard to not read more into it thanthe poster means.


I'm not sure I'm understanding this correctly (entirely possible), but, just in case, let me restate that I sincerely hope that you weren't offended. No ill will, scout's honor. 

I see in your signature that you are a Disabled Vet. I too am a Disabled Vet. Navy. And proud.

~Snax


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## DonJones

The one you broke sounds like the Hanna one that I'm saving up to buy.  I think the one I'm looking at also give the solution temp as well as compensating for the temp.

What I was trying to say is usually I'm not offended by someone challenging anything I post.  I also try to remind readers frequently to be skeptical of anything they read, especially my posts, and if it doesn't make sense then check it out.  About the only time I get offended is when someone can't give a source for their opinion and become obnoxious neither of which apply to your posts.  Your posts are well thought out, documented and usually over my head and I'm at least average in general knowledge even though I just getting started learning about growing.  Fortunately I worked on my grandparent's farm until I turned 18 and moved away, so that gives me a little bit of general growing knowledge and have some local old timers here in town that try to be very helpful, but unfortunately, most of them are outdoor stealth growers with little knowledge about hydro or some of the newer techniques.  For example, none of them had even heard about autoflowering varieties. 

I'm an Air Force vet myself and proud of serving my country but not particularly proud of having been in the Air Force -- in fact I frequently call it the Air Farce because the discipline was erratic at best and most of the crap we put up with came from drunk E-9s that couldn't hold a job anywhere else.

Not to worry, if I'm offended, you will know it. Oh another thing that lights my fire is when someone starts being obnoxious to some one else.  My pet peeve is when people use the forums to visit with each other in the middleof a thread rather than using PM for visiting.

Good smoking!


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## snaxforgandhi

DonJones said:
			
		

> The one you broke sounds like the Hanna one that I'm saving up to buy. I think the one I'm looking at also give the solution temp as well as compensating for the temp.


Mine's the Hanna HI-98129 and, yes, it gives solution temp as well as automatically compensating for temp when measuring pH and EC/TDS, something they call "ATC." Plus, you can specify the conversion factor for the EC/TDS measurements from 0.45 to 1.00, and you can do the same for the temp compensation coefficient beta, selection range being from 0 to like 2.4 or 2.5. On top of that it holds programs for single, double, or triple point pH cal, and single or double EC/TDS cal. It's freakin' awesome! Like I said, it has totally spoiled me. You're gonna love yours!

Word of warning from the genius who broke his! The ion permeable glass they make the pH electrode from is extremely thin and fragile! (At least mine was) I was used to my older Hanna that had a really sturdy glass 'trode with a permeable ceramic plug in the end. It was pretty much idiot-proof. Not so with the new one! Thank God the electrode is a replaceable cartridge. My new rule will be, "Never touch the 'trode with anything but liquid, e.g. nutes, cleaner, cal solution, etc.

I hope to see you at the Coffee Table so we can chew the fat about this and that. 

~Snax (He Who Lurks)


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## Droopy Dog

Da bump.

DD


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## ta2dguy

great thread, i buy a litre of phdown for $9.99 canadian and have never made my own but am a nut for scientific/chemistry talk. i know this thread is old too but who cares, lotsa great info here and not just about home made ph down. i need a good session with my volcano after that read .


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## Droopy Dog

ta2dguy said:
			
		

> great thread, i buy a litre of phdown for $9.99 canadian and have never made my own but am a nut for scientific/chemistry talk. i know this thread is old too but who cares, lotsa great info here and not just about home made ph down. i need a good session with my volcano after that read .



I started to buy some pH down, remembered Tater's thread and bought a qt of 'battery acid, fluid' for $6.75.

Haven't opened it yet, but pretty sure it's the solution and not the concentrate.  The nitty gritty details are inside the box, but it does say Battery Fluid, Acid on another place on the box.

I don't need much, but it just irks me to buy pre mixed anything and pay all those $$$ for mostly water.:rant: 

DD


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## snaxforgandhi

ta2dguy said:
			
		

> ... i know this thread is old too but who cares, lotsa great info here and not just about home made ph down. i need a good session with my volcano after that read .


 
Some things grow even better with age  

~Snax


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## snaxforgandhi

Droopy Dog said:
			
		

> ...Haven't opened it yet, but pretty sure it's the solution and not the concentrate. The nitty gritty details are inside the box, but it does say Battery Fluid, Acid on another place on the box...


 
I suspect you're correct, usually the term "fluid" indicates the 33% _premix_. And I agree that paying so much for premixed, mostly water "down" chaps at one's, er... hide.

~Snax


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## Droopy Dog

snaxforgandhi said:
			
		

> I suspect you're correct, usually the term "fluid" indicates the 33% _premix_. And I agree that paying so much for premixed, mostly water "down" chaps at one's, er... hide.
> 
> ~Snax



Yes, it's exactly the same as Fig's 1&2 that you posted.

DD


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## DonJones

*EVERYONE,*

I corrected my earlier post so please be sure to reread it before you use a 1/3 mixture of battery fluid, acid to H2O! * DO NOT USE THE 1 TO 3 RATIO!! IT IS NOT SAFE FOR GENERAL USE!!*

*The correct ratio is 1 to 8.46 (100 ml Acid to 846 ml H2O gives one US quart.)*  I really don't know where the 1 to 3 ratio came from but anywhere over a 5% solution is too hot to be using for PH down or storing around the house.  I just found my notes and discovered that when I was trying to determine what ratio to use, I started at 1 to 3 and found it too sensitive to be practical for PH adjusting.  I finally settled on the 1 to 8.46 ratio which gives me approximately a 3.48% mixture, which is still pretty hot, but it is easy to remember, just put 846 ml of H2O in a marked quart container and slowly add 100 ml of battery fluid, acid to it.  I have a quart jar that I use to store the PH adjusting solution in that has a mark at both 846 ml and 946 ml- 1US quart.  That makes it real easy to use to mix a new batch up.  It also pretty much insures that I'm not going to get the mixture to strong unless I short the amount of H2O that I put in the jar or over fill it with acid. (I usually use a large syringe to measure and add the battery fluid/acid because I find I can control it easier that way. It is a little slower than pouring it, but a lot more accurate and since I've retired I have plenty of time on my hands anyway.)

Until I can find a reasonable price and source for graduated cylinders -- ANY SUGGESTIONS ANYONE? --, I'll continue to use syringes obtained from the local veterinary supply/feed store.

Here is an update on adjusting the PH before adding nutrients or after. I have finally acquired a reliable Hanna PH pen (even color challenged people like me can read the numbers on the digital readout) and have checked the final PH doing it both ways.  I find that my error batch to batch is larger than the difference in when I put the PH down in.  That is in line with what the manufacturer for FHD/Holland's Secret nutrients told me about their nutrients.   

I have found it easier to put 4 gallons of tape water in a 5 gallon bucket, pour it back and forth between two bucket several times to aerate the water and hopefully dissipate most of the chlorine, let it sit for about 1/2 hour or so, then add my nutrients and acid all at the same time, then aerate it some more by pouring it back and forth -- which also thoroughly mixes the solution up, let it set for 15 minutes to 30 minutes, then check both the PH and PPMs to be sure I didn't screw up.  If it turns out okay, then I start feeding the plants with it. This method works great with both the veg and flowering mixtures.  Once I get the carbon filter installed in the water supply to remove the chlorine, I will be able to skip the first aeration step along with the first sitting step.  As our operation grows, I'll probably substitue using a paint mixer on a cordless drill to mix the H2O, niutrients and PH down instead of puring it back and forth.  Plus it will be a lot easier on our backs.

I APOLOGIZE FOR THE ERROR IN MY ORIGINAL POST ABOUT MY RATIO OF DILUTION FROM BATTERY FLUID TO PH DOWN.  HOPEFULLY NO ONE TRIED USING THAT RATIO.  ONCE AGAIN THE CORRECT DILUTION RATIO FOR WHAT I USE IS 100 ML OF BATTERY FLUID ADDED TO 846 ML OF H2O AND GENTLY AGITATED TO THOROUGHLY MIX IT.  This is a HOT mixture and UNLESS you really watch what your doing ALL THE TIME it would be better to use one of the mixtures that Snax posted at the start of the thread!

Again, I'm really sorry for the bad information I posted.


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