pH issue

hey guys, i'm having a problem maintaining the pH in my reservoir. i'll check it and it will be 6.5-6.8. i'll lower it using pH down chemicals to 5.5. in 4-5 hours it will jump back up to 6.5-6.8 and sometimes higher. what could cause the pH in my water to jump like that? the leaves on my plants are showing nute burn and i think it's because i cannot maintain a pH that is suitable.

appreciate the help.



here are the details of my setup:

1. plants are in the vegatative stage started from clones. they are around 2 1/2 weeks old.

2. using a drip hydroponic system. i'm watering them 5 times during the day for 15 minutes each time.

3. i have a light proof (well almost, damn close) tent made with panda
liner and PVC pipes that is 5' x 5' x 6 1/2' high. On the inside of the tent on the lower half i have a reflective material I got at the hydro store that has a bunch of little pyramids on it. seems to work well.

4. I also have a carbon filter that connects to to the light and then a
fan via duct that helps keep the tent cooler and provides circulation. it is on when the lights are on.

5. average temp is around 78 degrees farenheit...the humidity is around 50-60%

6. i have a 400 watt MH bulb with a digital ballast that sits about 16 inches over the tops of the plants that sit in a 3' x 3' drip tray. light is on for 18 hours and off for 6 hours. on at 4AM off at 10PM.

7. I have a reservoir that sits under the tray that is i think 10 gallons and is a dark grey plastic...I only use distilled water. I also have an aerating stone in the reservoir with the water pump.

8. i'm using GH Flora Nova nutes, right now only using the grow, not
bloom.

9. currently, my PPM is 150. i'm using a sunleaves PPM meter and a Hanna PH checker

10. grow media is hydroton and i let it sit in pH balanced water for 24 hours before planting in it.

12. all the plants are white widow (at least thats what the seed bank
was supposed to send me)

Nute burn has nothing to do with your ph, it as to do with over fert. IF your ph is to low or to high it will cause your plant to "lock up" certain vital nutes and that may at times look like nute burn but it is a deficiency of sort, cant tell with no pic. If the water in your rez is to hot, and you do not have enouth oxigen in your rez, your plants will die, and it will look like nute burn, well almost.
You need to stabalize your ph, a certain swing going up is good, from say 5.2 to 6 or so but very slow, fast changes to your ph will ruin your garden.

If your ec is to low it will also drive the ph to keep rising fast because your plants are feeding and there is not enouth food in the water, Im not a tech guy that is my simple explanation, also if your tap water is not to "hard" try using tap water versus distiled or ro water, that can also help your ph to be more stable.

I would empty your rez and clean up, and I mean clean EVERYTHING and put the clones back in a new CLEAN enviroment, also add some hydrogen peroxide to your rez, I use 1 cap full per galon in a small rez or 1/2 cup for every 20 galons every 4 days.

Make sure the water in your rez is at about 68 degrees F, never higher than 75 degrees F

You also need a lot of air moving in and out of your garden, everything must be at 100% or the garden will fail.

I had a few issues like this also. I'm a soil guy, but my ph treated watering reservoir would return to a higher ph after 24 hours. I started using a new type of ph-down and have had no issues. However, I switched to GH so this may not be the answer. In soil I have the advantage of adding stabilizers to the medium helping to easier maintain the numbers. Also, I've had a bad batch of nutes before. I tested the water after adding each nute individually and found my grow would drive the ph up like crazy - beyond normal. After replacing it, things were much easier to control. You may want to try going even lower with your ph and see if it stabilizes at a higher number. Best of luck - hope I helped a little. peace

Did you rinse your hydroton out before you used it? It's always good to soak and rinse that stuff out before use.
Also what Pepper said about your low EC is very important.

pepper: i have attached some pictures. so, you think that my PPM might be to low at 150? I dont have an ec meter only PPM. what should my PPM be?

my tent has plenty of circulation.

i will clean everything up and put the clones back in there. i've never heard of using hydrogen peroxide, but i'll try that too.

the water at the house is not hard as far as I know. I can switch to that.

the temp of the water in my res is usually between 70-72 degrees Fahrenheit so that should be ok.

barbapopa: 10. grow media is hydroton and i let it sit in pH balanced water for 24 hours before planting in it.

i appreciate everybody's assistance.

You do not have nute burn, you have the oposite you have nute deficiencies. It looks like to me that you have a potassium deficiency. I'm assuming your clones have a nice root system already, bring your ppm up to 350/400 for 1 wk, in about 3 to 5 days your plants should start to look better, after 7 days change the rez clean EVERYTHING again and bump the ppm up to 550/600, they should look ever better then.

Your clones also look pale green to me wich tells me your nitrogen levels are also to low, you want your plants to be a nice deep green, but not a dark green almost black if you can understand what I mean thats to much nitrogen.
I know its a paing getting these nutes right. Do not allow light to hit your water in the rez, do not keep your rez uncovered, use a black rez, or make it 100% light proff.

Potassium is involved in maintaining the water status of the plant and the tugor pressure of it's cells and the opening and closing of the stomata. Potassium is required in the accumulation and translocation of carbohydrates. Lack of potassium will reduce yield and quality.

Potassium deficiency (K).

Older leaves are initially chlorotic but soon develop dark necrotic lesions (dead tissue). First apparent on the tips and margins of the leaves. Stem and branches may become weak and easily broken, the plant may also stretch. The plant will become susceptible to disease and toxicity. In addition to appearing to look like iron deficiency, the tips of the leaves curl and the edges burn and die.

Potassium - Too much sodium (Na) displaces K, causing a K deficiency. Sources of high salinity are: baking soda (sodium bicarbonate "pH-up"), too much manure, and the use of water-softening filters (which should not be used). If the problem is Na, flush the soil. K can get locked up from too much Ca or ammonium nitrogen, and possibly cold weather.

you're the man. i will do that and report back in a week.

surreptitious said:

you're the man. i will do that and report back in a week.

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Sounds good

I have the same prob at first with Hydroton...I soak it in pH'd water, but it still raises pH for the first week or so but it adjusts...

cmd420 said:

I have the same prob at first with Hydroton...I soak it in pH'd water, but it still raises pH for the first week or so but it adjusts...

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Hydroton does nothing to ph levels, unless it has been used in another garden, and was not cleaned properly, also no need to pre soak hydroton in ph'd water, you can do it but it's a waist of time.

When hydroton is new out of the bag it must be rinsed out really well, until the water washing the hydroton is clean, no sign of red dust, that is all you need to do, very simple.

If you are going to use hydroton that was used in a previous garden, you need to wash it out by first rinsing it just like you would with new hydroton out of the bag, BUT you also need to soak it in a clean container with clearex added to the water, this will remove any salt build up in your hydroton, then rinse again under clean water.

Hmmmm..

I have been growing with Hydroton and I find that my pH tends to rise for the first few weeks, then levels off, then I have to start adjusting it up.....

I've never used "used" hydroton...

I rinse my hydroton 6 cups at a time...until water from those six cups runs clear....

...so, pray tell, what is going on (that explains all of these factors) if it's not Hydroton...(not challenging you Pepper, just curious for a dofferent answer)

cmd420 said:

Hmmmm..

I have been growing with Hydroton and I find that my pH tends to rise for the first few weeks, then levels off, then I have to start adjusting it up.....

I've never used "used" hydroton...

I rinse my hydroton 6 cups at a time...until water from those six cups runs clear....

...so, pray tell, what is going on (that explains all of these factors) if it's not Hydroton...(not challenging you Pepper, just curious for a dofferent answer)

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If you need to adjust your ph on a clean new rez it could be a couple of things, my first guess is that your ec level is to low, if the ph is good at first and then it starts to rise that means the ec level is droping due to the plants feeding and that is good, if you need to raise your ph then that is not good that means your plants are not feeding, its time to clean and change the rez or raise your ec.
Those would be the 2 things I would look at first, also excessive salt build up in your root system or rez will throw your ph all over the place, in that case its time for a good cleaning, flush your system using clearex, and start fresh, new water and new nutes.

10 -4...I'll look into EC as it relates to pH..thx

cmd420 said:

10 -4...I'll look into EC as it relates to pH..thx

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I'll give you another for you to scrach your head on

During vegge plants will release toxins that raise ph, during flower plants release toxins that lower ph.

You confused yet No need to be either way the system needs to be taken care of, what I posted initialy are the first things you should look out for, I'm just letting you know of this to.

so, it's normal to have to adjust the pH daily?

surreptitious said:

so, it's normal to have to adjust the pH daily?

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Yes, and no

To much ph fluctuation is not good period, specially it if its fast, a slow rise in ph is good.

Growing hydroponicly is a pain in the arse until you learn your equipment/garden, once you learn what your equipment and garden can do or cant do, then it become easy, but even very experianced hydro farmers have dificult times with their grows, it is not always "peaches and cream"

You can feed your plants with the correct amount of nutes, water and air temps are right, everything is dialed in nice, but if your ph is out of wack your garden will fail.

ok, i'm still experiencing fast raise in pH. any other suggestions?

I have four sativas in 12/12 that have the pH go up nearly every day

....I have four indicas in 12/12 that go down in pH every day....

I can dig on what Pepper is saying about the differences in a plant's respiration with respect to the stage of life it's in, BUT...

what's the deal with the daily pH fluctuations? I am in the same boat as Surrepititous...

surreptitious said:

ok, i'm still experiencing fast raise in pH. any other suggestions?

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That tells me nothing. What changes did you do to your garden? What is the initial ph, are you using tap water, did you CLEAN EVERYTHING? And I dont mean just rinse everything off, I'm talking about alcohol, clearex, hydrogen peroxide, a good cleaning.
Pics?

that's the thing..I don't just clean the stuff, I replace all tubing, fittings etc..

and as for my buckets, I use FloraClean and FloraShield soakings and scrubbings...

I don't use a rez, I just top off as needed...

my tap water is at like 7.0 (ish) and it's ppms are around 50 or so....

I hope I'm not jacking this thread, but I think others have these issues as well....

c'mon Pepper..stay with me...what ya got next?