CO2 and PH drop - tweaking sealed rooms

In another thread a few of us noticed that running sealed rooms with CO2, that the PH of the res would drop to low 5's and high 4's and while discussing it, we came to the theory that CO2 was becoming suspended/disolved in the nute solution (possibly forming carbonic acid) and therefore lowering PH. There seems to be very limited buffering of the solution to this PH as it's easily corrected with a little PH up or Potassium Silicate and doesn't affect the EC/PPM/TDS.

So what we're gonna do here is a little experimenting and contemplation on ways to minimize the PH changes and see if we can't learn a thing or two in the process

Details of my setup:

2K over 4x8 coco SOG
18K Whirlpool AC
32pt Whirlpool dehum - drains to res @ 8-10ppm to top off
28 gallon res with FF & Botanicare nutes/additives in flowering room
Bottled CO2 at 1200ppm
85-90f during lights on and 65-75 lights off
55% RH
Feeding at 5.7-5.8, PH drops to 4.6-5.1 after 3 days (ppm's drop ~200-250 during this 3 day period).

Bree, Skeletor & VT (and others of course) please jump in with your specs/findings and we'll get started on this little project and see what we can learn from it.

CO2 injection

CO2 injection

I observed the same thing in a DWC grow in a sealed room with CO2.

Since the roots didn't need any CO2, I moved my air pump out of the sealed room so that fresh air was pumping through the air stones instead of CO2 enriched air. My pH drift went away.

Does a lid on the res help any? Or atleast slowdown the drop rate of the pH?

Indica Sativa said:

Does a lid on the res help any? Or atleast slowdown the drop rate of the pH?

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Dunno...I've got a lid on mine, but there's also a gaping hole in it for my return drain and for the plumbing that comes outta it. I'd imagine that pretty much any air in the room is getting elevated CO2 levels unless it's in something that's sealed air tight like a mason jar.

I'm gonna try moving my air pumps out of the room tomorrow...if that doesn't help much after a few days to a week I'm going to try moving the res out of the grow room and see how that affects things.

Thanks Sandman for coming up with this thread and idea....

Thanks Sandman for coming up with this thread and idea....

There are more things to consider than just the issue of pH drift.

Thanks Fonda-- for confirming what several of us already noted in another thread that lead to this one. It is definite.

Indica Sativa-- a lid would not help unless completely sealed to the atmosphere of the increased CO2, all gases and electrolytes will diffuse from an area of greater concentration to areas of lesser concentration. If you are using air pumps to bubble the reservoir you are actually actively causing the uptake of the CO2 into the water just like you are intending with the O2 by bubblers.

Sandman--I shut my CO2 down just to check what would happen to see if the indications from my past logs were correct. pH back to where it was expected without the Co2 so I definitely think we can say that is confirmed.

I would like to say something I said in the other thread we had going for conversation topic. I am by profession an expert in human physiology and cellular functions. I say this so you know why I make the analogies and where I am drawing my concepts from...... When a person is being resuscitated like in CPR, the intracellular acidic pH gets to a point where most most drugs do not work because most drugs work by causing anions and cations or for our discussion electrolytes/nutrients to shift in and out of the cell, thus altering their function or preventing them from functioning normally. This is due to lactic acid build up that becomes carbonic acid and eventually CO2 if the patient is ventilated and blood circulated. The point being, the intracellular acidosis caused by increased intracellular CO2 effects the shift of nutrient across the root cell walls or at least alters it just like it does in a cardiac cell or a patient. Since roots do not need CO2, these potentially negative effects are absolutely unnecessary.( Nutrient lockout, nutrient mismatch, Mg-Cal-K mismatch due to adjusting res. with pH-up, potassium hydroxide, potassium carbonate)

The other issue is that water has a finite capacity for holding dissolved gases. It is possible that by dissolving the unnecessary CO2 we are bubbling or atmospherically adding to the reservoir, could be preventing or displacing O2 suspension in the reservoir.

Any of these would not necessarily decrease root health but could definitely affect plant uptake of nutrients in optimal proportions that we are delivering them in and I might add paying a nice price for and to maintain.

The theories and concepts are sound and established science, the application to plants and effects are not established or proven. We need to discuss this and investigate it. It effects two of the three main points of our plants optimal growth.....nutrients and CO2. Each of these are costly.

Peace

Interesting thread here MTF Sandman

If you have a look at REAL aquaponics and aquaculture, where large fish populations are confined to relatively small sized reservoirs, the water has to be aggressively aerated in order to keep the water "de-gassed" so that the pH will not go out of control.

The fish put co2 into the water as a biproduct of their respiration. Normally this isnt a problem for the average aquarium keeper and the water aeration a standard aquarium provides, but when it comes to a properly done aquaponics setup, where the fish population is kept very high thruout the vegetative growth stage, the water MUST BE very aggressively aerated to keep the pH in check or fish AND plants will die.

So I agree completely with the hypothesis of this thread.
In a co2 supplimented space it is a very good idea to remote the air pump (source) out of the room, and better yet the entire res and air pump combination.

btw, keeping the air pumps out of the intense light is also great to help keep res temps down.
Obviously remoting the res outside of the warm room has benefits too.

cool just in the middle of setting up my co2. I will move my airpumps into the other room with my res. Thanks for this info. Makes alot of sense.

A question I have...

Even if the airpumps are located outside the room, Won't the ambient CO2 in the enriched environment diffuse into the reservoirs over time? Albeit, not as quickly... but it should still take place assuming the reservoir is turbulent... as it should be.

Great discussion....

If using chem nutes....I''m wondering if the use of GAC filters (Granulated Activated Carbon Filters), and thus removing VOC's (Volatile Organic Chemicals) would affect the PH.

I've also read in the forums that CO2 reacts with calcium in hard water...causing PH to rise....not sure if it has any bearing on this discussion...but using source water with a significant Ca content, seemingly would produce adverse effects on PH, if pumping in Co2 enriched air....

On the other thread dehumidifier water was brought up...and how the PH is much lower....(I feed my plants dehumidifier water)....so I have a hypothesis that if this water were filtered through a GAC...the PH would get closer to 7....

Just tossing out those ideas/thoughts....I am not proficient in any of these areas but do find this discussion interesting....gonna tag along

peace

I'll toss in my DWC, I also see this cycle in bloom, but with no co2, and a wide open room. I've been dealing with it by using high addback - 8+ -and I need a better solution. I will stay tuned, good thread.
H

Great discussion eveyone.......

Great discussion eveyone.......

10K-- that is some really good information and helps confirm the hypothesis we started with. The fact that many of us put our bubbler pumps on the floor were the ambient CO2 is more concentrated even complicates the problem more.

Neptune-- It definitely will cause diffusion across the surface to the reservoir. Think of it like a mountain lake. It has less dissolved oxygen in the water due to the different surface pressures of the oxygen at sea level as apposed to 10,000 ft. By increasing the amount of atmospheric CO2 you would definitely cause the diffusion of CO2 from the greater concentration in the atmosphere into the lesser concentration in the res..... and turbulence will increase this rate due to increasing surface area for diffusion.

VT-- that definitely makes sense. I think if using supplemental CO2 it may have to be considered what grow system to use and how to supply the O2 to the proper places and the Co2 to the proper places and limiting mixture.

Haps there can be many reasons for pH shifts other than CO2 like microbial ( good and bad) respiration, interaction between additives, etc. Increasing the phosphorus that is not quite correctly buffered right can cause this as well as the plants utilizing the ph-up potassium for nutrients due to imbalances and hidden hunger.

Thanks for all the excellent discourse.....

Peace

Seems like this is a more common issue than I originally thought...let's try working on the other side of this as well to try to eliminate some possible causes...

Is there anyone running a sealed room w/CO2 that has res and air pumps in the room that doesn't experience the PH drop?

Mucho kudos to everyone for thier input

controllerpiece of shit though.piece of shit though.

controllerpiece of shit though.piece of shit though.

Me.

Sealed room with AC/Dehumidier, Heater/Humidifier fully automated.

3000W cool tubes hung vertically external intake.

CO2, pumps right next to the buckets in the same room.

I run 100 gallon aquarium pumps for each individual bucket kind of over kill but it damn near doubled my growth from when I used 20 gallon models.

I use GH Flora Nova, I don't own a pH/PPM meter, I don't check either, I just follow the directions on the bottle and never had a problem yet the plants are super dark emerald green always painfully healthy.

I don't even have pH up or down.

Don't need it with decent water and a buffered nutrient in my opinion.

If I had to adjust pH every day I would have gone back to soil long ago.

Pump out the controller once a week, replace with fresh nutes, no problems.

Don't even have my home depot buckets light proofed at all I use the orange ones.

If I ever had a serious problem (I haven't yet since going hydro) I would just immediately change out the buckets with fresh nutes.

In my opinion people spend way to much time chasing pH when if you just mix up your nutes right, keep them topped off with a float valve, and replace the nutes every week you have no problems, at least I know I don't.

That is what the hydro guy at the store told me to do way back when, and it always worked so far.

I mean it really works.

I wish someone would try an experiment and do that without checking pH/PPM, or adding any pH up/down.

The guy at my hydro shop opened it up in '82 been growing hydro for 20 some years.

I am a firm believer in the philosophy that you setup the climate, you fill up your buckets with fresh nutes every week, you chop and dry when mature, and other than that humans are our plant's worst enemy.

I could probably train a monkey to maintain the grow at this point in the game.

I am lazy though.

P.S.

Are you using Fox Farm Tiger Bloom?

I know it has a low pH to begin with for storage purposes I think.

If you use Botanicare PBP that is buffered I think.

The guy at the hydro shop told me additives mess with the pH buffering.

I don't know I use a stand alone buffered nute so my advice might not apply to everyone sorry.

P.S.S.

I remember you from Overgrow you helped many people, big up, my man.

P.S.S.S.

I go off on tangents when I haven't slept in 24 hours.

I don't own a pH/PPM meter, I don't check either

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How would you know if your pH is dropping?

I sealed my room 100% starting about 6 months ago.

I would assume that if my pH has been out of range for 6 months I wouldn't be getting the results I am getting now, which are better than before I used CO2 and just had a boat load of ventilation.

I know my pH isn't dropping enough to effect the health of the plants, like I said they look great.

Unless we are talking about sproutco style "hidden" problems I can't see, but I don't know the yield and quality of my last two crops don't lie, all done using high levels of CO2 with no pH adjusting at all, just res change outs and staying topped up.

If they started to look bad I would change out the res with fresh nutes and try to isolate the problem right away, but it hasn't happened yet.

I just think people go crazy with the meters and the pH up/down and always trying to chase pH.

I started hydro to make things easier on myself not to be adjusting pH more often than I used to have to water in soil.

I am not the only one who thinks this way like I said I am just following the advice the hydro guy gave me, he said if you have to use pH up/down you are doing something wrong or you should get an RO unit because you have bad water.

Was just trying to pass on my personal experience everyone has their own style.

But like I said I really wish someone would try this out and tell me what they think.

I don't think they will notice a single bit of difference from when they used to be adding pH up/down all the time hell I would bet you will find your plants are even healthier just mixing your nutes once a week and forgetting about pH.

Just try it once please.

Mix up a fresh batch of nutes and don't adjust pH for a whole week until you change out the res.

If you see any problems at all you can change it out again and go back to chasing pH and disregard everything I said.

I am telling you though you won't see a difference at all, I bet you will even see a slight improvement from not messing with the pH.

Lurkerguy,

You have no real understanding what is actually happening in your reservoir, becuase you do not measure. No meter, no validity. If someone were to take your advise and try growing mj plants in a water PH of 5.0, or 4.8, they would be surely surprised at their rate of failure.

How do we know your PH isn't a perfect 5.9?
I can promise you, people chase PH for a good reason.

This is no simple matter of "just ignore it."
Your points are valid, I do agree that people can relax a bit more than they do, but CO2 enriched rooms with water PH 4.8-5.2 are not ideal. You are counteracting the CO2 enrichment by setting off the water PH... not a 100% trade, but you are definatly taking some efficiency out of your growroom. Stable 5.8-6.2 PH with CO2 enrichment is MEGA GOOD. Wheras, stable 4.8-5.2 PH with CO2 enrichment is NOT AS GOOD,

seen?

If my pH was 4.8 for the last 6 months my plants would be totally horrible, not just less than perfectly dialed in.

I just tested my pH with the GH liquid tester kit I haven't used in ages.

The color is very, very bright yellow so it must be close to 6.0 which is exactly what GH buffers set it to with quality water.

All I am saying is that since using CO2 my yields improved slightly and my veg time improved a whole lot so I am not using CO2 just to get the same results I used to get with ventilation.

So many factors can effect pH like water quality and additives mostly.

If you run RO water with GH Flora Nova or PBP or any other pH buffered nutrient CO2 will have absolutely zero effect on the pH of bubbler's.

He asked if anyone was not having a problem with pH in a CO2 sealed room and I am not having any.

I think the pH drop might be from something else I don't know too many factors to try and narrow it down.

I would be very interested to see what additives people who are having problems are running and if they use RO water and if not what the starting pH of their tap water is.

If everyone who spent money on a pH meter just spent that money on an RO unit and ran a single stand alone pH buffered nutrient with no additives I don't think anyone would have pH issues ever.

Just my opinion.

P.S.

As a side note using over sized air pumps is one thing I can say 100% makes a huge difference.

The more bubble's the better.

Every time I added bigger air pumps to my bubbler's they grew faster.

My last change of switching from 20 gallon models to 100 gallon models made an incredible difference.

Also I am not a fan at all of using one big air pump and running lines to every bucket.

I notice a large drop in air power as the length of the air tubing gets longer.

Take a 100 gallon aquarium pump and set it right next to one of your buckets and run air tubing into that one bucket as an experiment.

You will be shocked.

It all most gives aeroponics a run for its money if you use a big enough pump and limit the length of the line.

It is the same principal as keeping your ducting as short as possible for the cool tubes.

lurkerguy said:

If you run RO water with GH Flora Nova or PBP or any other pH buffered nutrient CO2 will have absolutely zero effect on the pH of bubbler's.

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lurkerguy said:

I think the pH drop might be from something else I don't know too many factors to try and narrow it down.

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lurkerguy said:

I would be very interested to see what additives people who are having problems are running and if they use RO water and if not what the starting pH of their tap water is.

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I'm running PBP bloom this round (PBP or FF previous rounds) with Calmag, LK, GreenFuse Bloom & Banana Manna in RO quality water (less than 20ppm at all times)...PH is dropping and nutes levels are also, so it's not a problem with overfeeding causing the PH to drop. Never had the PH drop like this using a vented setup and the same nutes tho, so it's pretty much gotta be an environmental factor and adding CO2 is about the only thing that has changed.

lurkerguy said:

If everyone who spent money on a pH meter just spent that money on an RO unit and ran a single stand alone pH buffered nutrient with no additives I don't think anyone would have pH issues ever.

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See above :wink: If I don't keep the PH up, within about a week I start getting PH spotting and nute lockouts...and I've got 2 60 gallon aquarium air pumps going into my res ATM...but it's not that big of a deal in my setup since the plants are in coco and have plenty of air contact within the medium - but I do it anyway just to make sure that I'm not depriving them of anything that could be beneficial.

PH meters are too cheap not to use for any grow...without one you're just hoping things stay good and if something goes wrong with the PH then you're a week or two behind the problem before you notice it.

I appreciate you're input Lurkerguy, but this thread is intended to resolve the issues of people running CO2 that are having PH drop problems - and accurate monitoring of the environment is required to diagnose, fix, and prevent these issues. Unfortunately we're not all blessed with holy RO water that autobuffers to the magic 5.9 no matter whats in the res nutrients or disolved/suspended particles wise. If you'd be kind enough to log some PH/PPM & CO2 PPM info with a digital meter, We'd love to see em so that we could better work on narrowing down the PH problems the rest of us are having.

Calmag, LK, GreenFuse Bloom & Banana Manna

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Have you tried running your res with just PBP Bloom and nothing else yet?

Additives can effect your nutrients ability to buffer itself.

Not only are you using a handful of additives, but many of them are from different manufacturers, and not even designed to work together.

I was told to avoid additives by the owner of a hydro shop who sells additives.

What does that tell you?

If you can afford a pH meter than you can afford to bless yourself with holy RO water as well.

I just checked my pH with the GH kit again, and it is bright yellow indicating 6.0 give or take.

P.S.

I never said to ignore problems at all.

If my plants started spotting I would change out the res and borrow an electronic meter right away.

With Flora Nova and RO water the pH just isn't an issue though.

I bet if I started putting additives into my res I would have problems right away.

Not only are many additives snake oil, but they can mess up your pH.

I would run your res with PBP Bloom and nothing else.

At the very least I would cut it down to PBP bloom, Bontanicare cal-mag, and LK at least they are the same manufacturer.

Additives are the root of most reservoir problems, this is true.

but we are at least agreed on the fact that CO2 enrichment in sealed rooms with bubbled reservoirs CAN cause problems for many folks.

MTF-Sandman,
First thing I would do is stick with PBP, Cal-mag, and LK. Forget than banana mana and greenfuse. If you are still seeing problems, try just running PBP solo. Foliar with LK.

Lurker,
A digital meter cost about $100.00 for the Hanna combo pen(ebay it from Sunstone Herbals), it's water proof, reads Temp/PH/EC/PPM. Very awesome probe.... and yes, we would ALL like to see your numbers.. before adding nutrients, after adding, and a week later(before flush). This is valuable data such that we can attempt to reproduce your results.


Good reading guys, keep the information flowing