# DWC/RDWC water temps and the fine art of salesmanship



## B3henry (Oct 29, 2017)

Water chiller salesmen say you got to have a chiller and people buy them, they cost hundreds of dollars. 
These water chillers are expensive to buy, expensive to operate and repair, noisy, take up valuable space in a closet, constant aggravation to deal with all this for what? 
So you plan to induce cold hypothermic res water conditions to do what?... to make the roots happy, to retard plant and beneficial microbe metabolism, slow down root, plant and microbial growth,  delay grow out time? 
Why in the world would any of you DWC/RDWC dudes do that? 
Because some water chiller salesman has absolutely convinced you that you got to have a chiller for some reason, right? And you bought it hook, line and sinker.
What in the world did the salesman tell you that made you spend all that money and buy his water chiller?
WHY?


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## B3henry (Oct 29, 2017)

Like... 

View attachment is+nothing+sacred.jpg


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## pcduck (Oct 29, 2017)

What is your solution? 
What are you trying to sell?

Scientific fact: colder water holds more DO.
Scientific fact: plant roots don't like high temps.


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## B3henry (Oct 30, 2017)

Feed the soil 
 . Hmmm, No disrespect toward dirt farmers dude, but you got to be one, NO? 
Most people are dirt farmers. Water farming is way too expensive and difficult, the chances of water farming failure is great compared to dirt farming. Its just a little more complicated.


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## Growdude (Oct 30, 2017)

B3henry said:


> Feed the soil
>  . Hmmm, No disrespect toward dirt farmers dude, but you got to be one, NO?
> Most people are dirt farmers. Water farming is way too expensive and difficult, the chances of water farming failure is great compared to dirt farming. Its just a little more complicated.


 
Its not expensive or difficult at all.

What are you trying to say, water chillers are a waste? you don't need low water temps?


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## pcduck (Oct 30, 2017)

B3henry said:


> Feed the soil
>  . Hmmm, No disrespect toward dirt farmers dude, but you got to be one, NO?
> Most people are dirt farmers. Water farming is way too expensive and difficult, the chances of water farming failure is great compared to dirt farming. Its just a little more complicated.



I agree with Growdude, not difficult or expensive at all.
I grew DWC for years before switching over to organics. Organics is much more difficult in my opinion. Organics is more then just throwing some seeds into some dirt. Between the two (DWC and organics) I have killed more plants and have killed them faster growing organically. 

But anyways,,,,


I am just confused as to what your solution is for high temps in reserviors besides using a chiller or any other method to cool the reservoir.


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## Hushpuppy (Oct 30, 2017)

I never saw a salesman when I needed a way to cool my rez (water above 74f and plants wilt and stop growing). I tried using ice in frozen 2ltr bottles but couldn't keep up. I searched for something online and found a water chiller... bought it, used it, love it. Water stays 68f-70f and plants are happy  

View attachment IMG_20171010_215633715_HDR.jpg


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## Hushpuppy (Oct 30, 2017)

Oh yeah that plant produced 9z by herself


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## B3henry (Oct 31, 2017)

This all began here. I read this piece about hydroponics, water temperature, cold water, water chillers and oxygen (O2, DO) a couple weeks or so ago. 
Thought about it a while, Googled some stuff and posted this thread, ask for other opinion and received a few. 

This cold water temperature talk, water chillers, yada, yada is 1 thing, but it looks to me like the meat of this matter is really all about vital elemental oxygen (O2) or more precisely, this is really all about trying to insure minimal safe dissolved oxygen concentration and dissolved oxygen saturation by cold nutrient water temperature. 
The cold water exercise is all about trying to maintain 9 PPM &#8211; 10 PPM @ 100% DO Saturation (safe DO) 24/7 for 3 months during a growing season. At least that the numbers everyone lloves to quote from the internet DO Charts. The DO chart numbers is never that same as the actual DO numbers revealed in real time DO test in functional grows and different stages of plant/root maturity and beneficial microbial colony maturity. Both eco system being aerobic, both eco system requiring and consume more O2 as they mature and grow. 

So this cold water is really all about elemental O2 (the most vital element dissolved in nutrient water), not the side show&#8230; water temperature or elemental nitrogen and elemental trace gases in ambient air that compose 79.1 % of the gases in air, air bubblers, waterfalls, water jets, water pumps, water chillers, air compressors or air ventures entraining ambient air into water pumps. 

Is the logic? - If you guessed that you need more oxygen because your roots are sick, dying and rotting or you think you caught a fungal infection somehow; you guess the cause of this problem is that your DO might be too low so you want to increase the DO stop the root suffocation. So you can either make the nutrient water colder or add more air, higher waterfall or both to be on the safe side of the DO chart to fix the low DO problem or kill the fungal infestation or trash the sick crop and try it again.

And, if you really want the absolute best oxygenation for DWC or FDWC, then they say that 13 PPM DO Concentration @ 100% DO Saturation is the best, that&#8217;s the best DO money can buy. But, that same DO Chart that every water chiller salesman quotes from as well as everyone else quotes says you can achieve this 13 PPM DO only with chilled, cold 50 F nutrient water. And that would probably require a $800 water chiller for a continuous 50 F chill job like this. 

The DO would be great, but, would this cold nutrient water negatively affect dissolved gas diffusion, water and nutrient diffusion in the roots and microbes cells in DWC/RDWC conditions? Hmmm&#8230; ? 

Personally, I would prefer the optimal, continuous 13 PPM DO in constant 77 F nutrient water because warmer water always = higher root/plant metabolism, healthier roots and most important &#8211; a faster grow-out time to harvest. The 13 PPM DO guarantees there will be no low oxygen problems in the nutrient water.

But, I understand that you can&#8217;t do this by guessing. Like pH and EC testing, you must test the DO and then adjust the DO up or down. That&#8217;s not adjusting the nutrient temperature up or down although there is a relationship between water temperature, salinity, gas partial pressure and gas % concentration 

HYDROPONICS
Water temperature ranges in hydroponic systems
Posted on August 16, 2012    by campo cultivator
http://www.growersguidetocannabis.com/water-temperature-ranges-hydroponics/ 

(so why do cannabis growers use hydroponic systems? Quite simply because given the right conditions, hydroponics enable bigger, quicker results than any others. Hydroponic grows &#8220;mainline&#8221; the nutrients, water and oxygen direct to where the plants can make use of them: the root system).

*What is the ideal hydroponic reservoir temperature?*

So why am I talking about oxygen when the subject matter is water temperature?
The temperature of water and its oxygen content are closely related, and the temperature of the solution needs to be fairly closely monitored in order to maintain dissolved oxygen levels. At low water temperatures, the plants go into shock, but as the temperature rises in the tank the solution loses the percentage ratio of its oxygen content. Here are some figures:

*tank temperature & % of oxygen in the solution (ppm)* 

10ºc (50ºf) 13 ppm [EXCELLENT DO CONCENTRATION RANGE &#8211; 100% DO SATURATION]

20ºc (68ºf) 9-10 ppm [OPTIMAL SAFE DO CONCENTRATION RANGE &#8211; 100% DO SATURATION]

30º (86ºf) 7 ppm [7 PPM DO CONCENTRATION RANGE &#8211; 100% DO SATURATION KILLS ROOTS &#8211; ROOTS SUFFOCATE, DIE AND PYTHIUM OUTBREAK IS PREDICTABLE]

As you can see the oxygen content in the resolution approximately halves for every 10ºc rise in solution temperatures.
ok got that! 

**In easy terms, ideal temps are between 18 and 20 ºc [64 F &#8211; 68 F] and if your water temps are anywhere near 25 -30ºc [77 F &#8211; 86 F] then the oxygen levels can be as much as half of the desired levels.

BUT
As a direct result of the water temperature being at higher temps the plants will need more oxygen at the roots so the problem is almost squared and there is 25-40 % less oxygen in the solution and the plants will need double the amount than normal. 

In real terms the effect is that the oxygen level in the solution is only at 25 % of the desired levels and you can chuck as much light or feeds at them as you like but if they are only running at 25% of the required dissolved oxygen levels then this is hardly conducive to happy healthy growth is it?

Some of the results of low oxygen levels in the rez tank are:
1.	roots are unable to work effectively, leading to:
2.	a build up of toxins meaning that the plant will be unable to take up the water and feeds needed for healthy growth
3.	The whole plant begins to deteriorate as photosynthesis and carbohydrate rates slow leading to wilting.
4.	Leaf damage and root die-back. Ethylene is released and causes a toxic overdose and the roots fail.
 And all of the above cause ideal conditions (especially in warm water) for every hydroponic growers worst enemy: PYTHIUM

[NOW COMES THIS WRITERS PIVOT FROM OXYGENATION TO WATER TEMPERATURE AND THE HARD SELL FOR WATER CHILLERS!]

***** So of course the real solution to high water temperatures in a hydroponic reservoir is a water chiller. **** *

We tried inserting bottles of ice water into the res tank but despite dedicating a small chest freezer to the production of ice, found it almost impossible to sufficiently and consistently cool our water (warmed by hot sunshine on the pipes outside). 
I
ts yet another expensive piece of kit to add to the grow room, but if you are growing hydroponically in an environment where water temperature rises either due to external environment (like ours) or internal environment (the tank is warmed by heat thrown out by your HPS), *then a water chiller IS be the only solution.*[

BUY A WATER CHILLER BECAUSE COLD WATER TEMPERATURE IS THE ONLY SOLUTION THAT WILL INSURE SAFE OXYGENATION AND PREVENTING LOW OXYGEN INSULTS, ROOT SUFFOCATION,FUNGAL OUTBREAKS, FAILURE, YADA, YADA, YADA.]

It is well documented in the horticulture scientific literature that in DWC/RDWC hydroponic farming that low dissolved oxygen in circulating  nutrient water creates the ideal conditions predisposing root suffocation, sick roots, root death, root decay, root rot which is the required condition inviting invasions and colonization from fungal opportunist like Pythium and other fungal outbreaks. Pythium does not thrive and colonize in oxygen rich res water containing healthy roots and healthy beneficial aerobic microbes.

And most dudes really believe that a $300-$400 water chiller IS THE ONLY SOLUTION there is in the 21st century that will insure safe oxygenation (9 PPM &#8211; 13 PPM DO)&#8230; &#8220;Is Nothing Sacred?&#8221; 

***How many of you DWC/RDWC dudes have ever actually tested your nutrient water temperature with a thermometer, pH, EC with a pH/EC meter? 

***How many of you DWC/RDWC dudes have ever actually tested your nutrient DO Concentration and DO Saturation with a DO Meter? 

Hmmm&#8230; even the most armature dudes should know that if you don&#8217;t test your nutrient water in DWC/RDWC you&#8217;re doing no more than guessing, hoping, preying at best.


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## Growdude (Oct 31, 2017)

So if you cant keep your res temps @ ~68f you need a chiller, thanks for sharing that.


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## pcduck (Nov 1, 2017)

:confused2:

@B3Henry 

Your copy and paste reply sort of bounces around quite a bit and I had to read it numerous time just to get a hint of what you are trying to convey. But here goes it.

100% saturation of DO is quite easy to achieve by adding a cheap air stone and a air pump. Your 77°  rez temps reaches 100% saturation of DO with a lesser amount of DO. Your 77° rez is just an invitation for pathologens, disease, and root rot because of the high temps that these organisms thrive at. Marijuana roots/plants grow better and produces more at a range of 65°-72°, also at these temps you will have more DO held in solution then at your 77° rez temps. So why do growers use chillers? The plants like the cooler temps (65°-72°),  more DO in the solution,  less chance of disease. 

I hope my explanation helps clarify your understanding of temps and DO. But if I were you I would definitely work on lowering that 77° rez temps. Lowering those temps will be the hardest and/or most expensive part of correcting your grow.:aok:


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## B3henry (Nov 1, 2017)

pcduck said:


> :confused2:
> 
> @B3Henry
> 
> ...


You might try reading this 1 more time begin here: So why am I talking about oxygen when the subject matter is water temperature?
If you were a hydroponic grower, do you think that the rhizome mass and beneficial bacteria in a DWC/RDWC would be healthy IF the DO is actually held constant 24/7 at 13 PPM or greater and the DO Saturation held constant at 100% - 110% @77 F  79  80 F water temperature?  I understand that this is far beyond the internet DO charts predictions and the charts do not address this, but lets just imagine for a second that these DO and water temperatures are really possible. 
But when the DO in reservoir water is tested under actually growing conditions and the  hydroponic system contains fresh water and 2 functional aerobic biomasses and you actually test the DO, you will find very different DO values vs. the DO Chart prediction values. The 2 aerobic eco systems living within DWC/RDWC life support systems are continuously consuming DO which is not subtracted from DO PPM and DO Sat the DO Chart values. 
More aerobic biomass (as the crop matures) always consumes more DO and that DO consumed per minute or per hour must be subtracted from the DO chart predictions. If the DO is not tested, you can guess, If the pH or EC is not tested, you can guess that too. If the water or air temperature is not tested, the only thing you can do is guess.
What do you think is the most vital element absolutely required continuously minute by minute for all aerobic plant roots and aerobic microorganisms in a DWC/RDWC life support system? Dissolved oxygen (O2), CO2, Nitrogen, magnesium, zinc, and chromium... chilled water?


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## pcduck (Nov 1, 2017)

Not sure what you are trying to convey, but here it goes.


Your ppm's of DO at 68° will be a greater amount then at 77° with both at 100% saturation. Has absolutely nothing to do with biomass, microorganisms and how fast they consume DO. 110% is unachievable unless you are testing under a large waterfall. Where the highly oxygenated water is forced many feet below water surface creating more pressure. This 110% saturation level would not occur for very long as it would dissipate upon rising to the surface.

If you cannot achieve 100% saturation of DO, buy some more/better air stones and a bigger/better air pump

 If you are trying to grow organically in DWC/RDWC, good luck with that as neither system lends itself to growing that way.

If you are just trying to convey that you can grow and are happy with the results @ 77° res temps, congratulations! That is you and you got lucky. But your results would be much better if you would lower your res temps to 68°. Doing this would increase the DO ppm's as cooler water is able to hold more DO then warmer water. Less chance of diseases and pathologens with cooler water also.

I hope my explanation helps your confusion with DO, temps and how they pertain to gardening.


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## B3henry (Nov 2, 2017)

Hey Duck, 
You are a pleasure to talk with you about these complicated things like effective oxygenation, refrigeration, hypothermia applied in DWC/RDWC hydroponics. I do chuckle harmlessly at some of your logic and reasoning from time to time and that&#8217;s OK, no fowl no harm. 

Elemental oxygen (O2) is an elusive gas. People are low tech, people cannot smell, taste, see or feel the difference between elemental O2 and ambient air although the difference between these gases is great.

A true story you might find interesting &#8211; A while back, I actually observed a peculiar interaction between a nurse, a doctor regarding a patient that need oxygen. The patient felt real bad, his lips turning blue, hospital room temperature around 75 F, The doctor ordered a nurse to give the patient oxygen with this nasal prong thing @ 3 LPM, the patient was turning blue and needed oxygen immediately. 

Well that nurse argued with the doctor in front of the patient about that doctors order for oxygen   in front of that patients family who was also in the room saying this patient was her friend, the patient was quiet poor and the family could not afford oxygen because oxygen is too expensive, that an electric fan was free. She told the patient and the patients&#8217; family that a large electric fan provided plenty oxygen for the patient&#8230; and they actually believed that nurse. 

Then that nurse told the doctor, the patient and patients family that 3 electric fan in the room blowing directly into the patients face would provide plenty oxygen for the patient, All that oxygen would make his lips return to pink (blue lips is a classic clinical symptom of low oxygen)&#8230; this story terminated 10 minutes later when the doctor called in that nursing supervisor who immediately fired the argumentative nurse on the spot. That nurse was   escorted out of the hospital by security.

The point of this story is that the nurse thought that more electric fans blowing more air would provide plenty of cheap oxygen and correct the patients low oxygen problem. In her simple way of thinking, she really thought air was oxygen. She really believed that several electric fans would provide plenty oxygen for the patient and stated that misconception as medical fact. Of course the doctor disagreed with her logic which would have endangered the patient life and that nurse was fired.

 I chuckle when I recall that event. The doctor plugged the O2 device into the wall O2 outlet himself, put the O2 mask on the patient face and turned the O2 on. The patient&#8217;s lips immediately turned from blue to pink after only several breaths of O2 with the O2 mask. The doctor was right, his patient was low on oxygen and needed more oxygen, not more ambient air.

That was a real Eureka experience for that nurse. The 2nd Eureka moment came a few minutes later when she was fired on the spot by the nursing supervisor. The difference between air and oxygen became crystal clear then, but that did not save her job at that hospital&#8230; she was just way too dangerous. Actually, I was told later that she was training on the job to become a Nurse&#8217;s Aid. She went to work at a VA hospital after that.

You might find this piece interesting: Professional hydroponic horticulturist also struggle with the DO problems too.

*Are you maintaining the proper oxygen levels in your hydroponic production system?*
By David Kuack on 05/30/2017 in Blog, News 

Growers have affordable options for ensuring plants receive sufficient oxygen in hydroponic production systems to maximize growth and to reduce the chances of disease.

https://hortamericas.com/blog/news/...-levels-in-your-hydroponic-production-system/ 

I have no confusion with Henrys Law regarding gas diffusion into water. People do often skip the part in the law about the importance of gas partial pressure or fail to understand that part of the chemistry law. 

As for all the aquatic aerobes that actually consume dissolved oxygen continuously in all DWC/RDWC life support systems, there is either not enough DO, enough DO or plenty DO. 

This is simple, like seeing blue lips that are deprived of oxygen or pink lips that are not deprived of oxygen, dying roots or healthy roots. When aerobes do not have enough DO (not dissolved air) continuously 24/7, microbes get sick and die, roots get sick, roots suffocation, root death, roots decay and rot and then fungal infestation comes.  

That low O2 problem is predictable and then may be reversed by a savvy grower that has the ability and knowledge to detect and correctly diagnose low DO correctly the fungal feast begins. It&#8217;s very cheap and really easy to kill fungi, but it is very difficult to resurrect plants with dead roots. That requires divine intervention&#8230; you got to really be tight with the Lord to pull off a root resurrection before the fungi eat those rotting roots?

I nearly forgot to mention&#8230; That nurse sued the hospital, the doctor and the nursing supervisor over that firing incident, the hospital settled with her out of court. The settlement was $150,000.00, not bad eh?

B3


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## pcduck (Nov 2, 2017)

Not sure how any of the above pertains to gardening.:confused2: Unless you are trying to sell an O2 injection system. Which is a waste, since 100% saturation is very inexpensive and easily achievable.:confused2:

But in gardening it does not take a "savvy grower" much effort or expense to achieve 100% DO saturation continuously.(air pump/air stones). The effort and/or expense comes from having to keep the rez solution at the temp the plants prefer and the pathologens don't.


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## Hushpuppy (Nov 2, 2017)

B3henry; are you an engineer? you sound like an engineer. The details of all the chemistry is fascinating for sure, but I think you are over thinking this, or maybe trying to invent something that is more complicated than necessary. When My plants get too warm, they aren't happy. when their water gets too warm, they REALLY aren't happy. When I keep them around 75f and their water right around 68f, they are happy. Happy plants make happy flowers


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## sopappy (Nov 6, 2017)

B3henry said:


> Water chiller salesmen say you got to have a chiller and people buy them, they cost hundreds of dollars.
> These water chillers are expensive to buy, expensive to operate and repair, noisy, take up valuable space in a closet, constant aggravation to deal with all this for what?
> So you plan to induce cold hypothermic res water conditions to do what?... to make the roots happy, to retard plant and beneficial microbe metabolism, slow down root, plant and microbial growth,  delay grow out time?
> Why in the world would any of you DWC/RDWC dudes do that?
> ...



I never even bothered concerning myself with water temperatures until I got pythium. That'll learn ya...


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## B3henry (Nov 11, 2017)

Appreciate everyone's participation, responses and ideas... thanks


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