The mysterious PH fluctuation

Indoor Growing Hydroponics
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Hello, I have an interesting story to share.

It is the Story of a Guy, who wanted to try Hydro with an Airpump. The Guy was an experienced Grower, but never tried the maybe simpliest thing. A Bucket, with an Airpump… So they Guy thought, hmm this is easy, I buy some simple Nutes and just try. Said, done. He adjusted the PH to 6.0 and did put a Clone into the upper hole of the Bucket. The Bubbler was turned on and he left the Room. The next day he went back into the Room and had to see the Clone was looking super droopy. He thought, the Roots were not getting enough Water, so he turned up the bubbeling and left the Room. 6 Hours later, he entered the Room and had no Idea, why the Clone wasn’t rehabilitating. So he checked the PH of the Solution and saw it was entering levels of 7,8. Well, I see, said the Grower, adjusted the PH again and left the Room. 1 Hour later he entered the Room again to make sure everything is right. And the Clone… had almost died.

WTF said the Grower to himself, how is this possible? He measured the PH again and voila 7,8.

So now it gets interesting. We are going to make a challenge out of it. The Grower checked a lot of things after that:

A.) It was simple, the temperatures were just to high, this caused the fluctuations.

B.) The Airpump was dirty inside! This caused the Fluctuation.

C.) There was something in the Tapwater…

D.) The Fertilizer was not for Hydro…

E.) There were some nasty Bacteria in the Room which were brought into the Water…

F.) A whole other Problem caused the Fluctuation. (Leave your educated guess.)

So, what do you think? ( The Problem was solved)

Leave your guess below. The Question will be answered by me if nobody ticks the right Letter.

Also I have to mention: It wasn’t me. But this could be interesting for everyone growing in Hydro or using an airpump to oxiginate water.

Have Fun and be well.

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A, He must Have Check this and know that its not the problem.

C, any chemicals?

or

B is my answer. It would be a really interesting thing to think about. But what Kind of dirt?

D, He couldnt be that wrong :smiley:

E, it would take Longer period of time to actualy damage the grow I think

F, He used something poisonus to clean the bucket? Or the plastic?

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What did he use to adjust pH?

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He needed to use buffered acid as he was in an extreme hard water area?

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i’ll guess b c or e !

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If you’re not taking about my hydro grow, you could be :slight_smile: I was having almost the same exact thing going on. Ph climbing back to near 7 from 5.5 in less than 8 hours.

Im not 100% sure what the cause is/was, but I have it under control now.

Its not my air pump - still using the same one.
Its not my nutes - still using the same Mega Crop.
Its not temp related - rez and root zones stay under 72 at all times.

I have no real idea about bacteria, but I doubt it. The entire system is brand new and was washed, and then was flushed with bleach and then flushed with fresh water. Plus my clones were almost killed with an over dose of neem oil, so I very much doubt they are the cause in my case.

That leaves C - the water and F - another thing. In my case the “other thing” is for sure the media I used.

I ran some tests and my lava rock, and my perlite and my tap water ALL raised PH over time - even after using GH PH Down to lower it.

What has worked for me is drastically lowering the PH - like to 3 - and letting the system circulate for several days, then flush the system and repeat. I also switched over to using sulfuric acid - which I have read works better at keeping PH down than other options.

Over the last few days, my PH fluctuations have improved to where they are almost gone. Instead of going from 5.5 to almost 7 in under 8 hours, its now almost stable for over 24 hours. Its gone up less than 0.1 in the last 24 hours.

So, Im guessing C or F and leaning more to F - media.

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Hmmm, let me get out my deerstalker hat and calabash pipe and think on this a spell.

A? Not possible. the only way the pH will fluctuate with temperature is if the temperature was fluctuating since pH goes up/down with temperature.

B? Possible.

C? Not possible. For that to be the cause, he’d have had to add more water after adjusting pH. An experienced grower would know not to do that.

D? Highly unlikely. For that to be the cause, he’d have had to add more feed after adjusting pH. An experienced grower would know not to do that.

E? Possible.

F? Unlikely. You’d be pretty sadistic to give us a list and the answer wasn’t in it. But, a bad battery or pH meter would be an obvious answer if it is not in the list.

The most likely cause is a source that is continuously adding something into the water, so bacteria is unlikely.

This leaves the air pump. How?

My tap water before my whole house filter is about 8.80 after the whole house filter, it is consistently 7.45 pH. Filtered further by my R.O. system, my pH is 6.35. This tells me that the more particulate matter there is in the water, the higher the pH gets. A dirty air pump would be pumping particles directly into the water, adding something new to the water constantly. The problem would be even worse if the dirt in the air pump contained calcium or lime.

So, my answer is: B, the air pump was dirty.

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if the water has lots of dissolved gases and minerals in it, the PH will rise as they leave the water

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@legalcanada: Yeah, you are right, something LEAVING the solution could also cause a fluctuation, I hadn’t even considered that scenario. In that respect, gases leaving would be a likely source of an increase of pH, if my assumption of minerals causing an increase in pH is correct. Then gases exiting would leave a higher concentration of minerals, thus raising ph. But as large of a change in pH as he was experiencing in as little as 1 hour makes me stick with my diagnosis of something mineral coming out of the air pump.

Can’t wait to find out what his actual cause was. I love puzzles.

There is no media. That is how this new problem came about. He was a soil grower, now he is a bubbler grower, everything he is using is unfamiliar to him. If he had had this problem in soil, he probably would have figured it out much more quickly.

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Actually it is possible - at least with my well water. I just did a test of my system. I took 4 glass jars and ran 4 tests.

  1. I took a gallon of tap water and PH’ed down to 5.11 with GH PH Down.
  2. then I poored that into the 4 jars.
  3. Then I added Lava rock to one jar, perlite to another jar and nutes to the 3rd jar and left the 4th jar with just the PH’ed tap water.

After 9 hours from the start:

The PH’ed water went from 5.11 to 5.18 = + .07
The PH’ed water plus lava rock went from 5.38 to 5.84 = + .46
The PH’ed water plus Perlite went from 5.34 to 5.71 = + .37
The PH’ed water plus nutes went from 4.93 to 4.97 = + .04

After another 10 hours of soaking, the readings this morning are as follows.

PH’ed Tap water alone has gone from 5.11 - 5.18 - 5.46 = + .35
Tap plus lava rock has gone from 5.38 - 5.84 - 6.25 = + .87
Tap plus perlite has gone from 5.34 - 5.71 - 6.10 = + .76
Tap plus nutes has gone from 4.93 - 4.97 - 5.62 = + .69

So it is very possible for tap water alone to go up in PH after you PH it down.

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Re-reading the first post, I get the strong impression he is hinting it was the airpump. But, Im having a hard time thinking of some contaminate in the pump that would raise PH like that AND that could be passed through the airlines and air stones.

Oil or lube in the pump shouldnt change PH at all, and the lube isnt even in contact with the air. Its separated by the diaphragm. If the diaphragm was punctured, he would get no air flow.

The only other possibility I can think of is maybe there was some powdery PH buffer material around the intake on the pump that got sucked in. Could he have placed the air pump near an open box of baking soda??? Doesnt seem likely :slight_smile:

If there was no medium, then maybe he was using some whimpy organic stuff to lower PH and it just wasnt lasting very long? :wink:

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the question is so tricky cause i could see all of them being plausible lol not likely but plausible

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@anon32470837, yes, as @legalcanada pointed out, I forgot to take gases exiting the water into consideration. In a all liquid hydro setup, gases are constantly leaving the water as they rise away from the water body.

Even so, it should eventually settle down. I have 2 tap water samples in jars along with sample of R.O. water. They are saved because I noticed a large increase of pH in a sample that had sat overnight. The 2nd sample is because I didn’t believe the first one was possible. The sample of R.O. water was to verify that reading after sitting.

The 2nd sample of tap water went up to 8.6 pH in only 3 hours, which is the same as the pH in the first sample that was 24 hours older. I found that it never changed again after that. I still check all 3 samples whenever I think of it. The pH of both tap samples is still 8.55-8.65, the old sample of R.O.water never changed at all.

That would seem to indicate that tap water will only go up so high and level off. Maybe the constant bubbling allows the water pH to go up so much due to evaporation and other gases escaping. It defies logic to say the pH can rise indefinitely though.

I still stand by the air pump. The one change occurred in only an hour. I believe something was being pumped into the water. An air pump can only pump air out if air is coming in. Maybe the little compressor was picking up dust from the floor. The only thing I am certain of is the little air compressor was constantly adding air to the water and that action could easily have been accommodated dirt and other mineral particles.

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I’m going with chemical off gassing for this one.

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You are close to the right answer!

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Its not just outgassing that will keep or raise the PH in water. Dissolved minerals can buffer the PH up or down depending on whats in the water. Things like limestone, chalk, and especially calcium carbonates - from sea shells, etc, can buffer the water. They will let the PH drop initially, but cause it to go back up as soon as all the acid you added is used up. The chemical reaction takes a little time depending on the exact chemical nature, the exact acid used to drop PH, other things in the water, temperature, etc.

Ok, which part? :slight_smile:

I think it time for you to come clean! :smiley:

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If it is a 5 gallon bucket with R.o water at 0 ppm and you added acid, that will take you on a ride for sure.

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Ok you are so close, here it is:

It is F.) none of the Above, but: The Stone connected to the Airpump laying in the Solution was a cheap Stone with Calcium-particles in it. This caused a super rapid fluctuation.

Why did I do this Letter mystery thing? To show some how wide spectred the world of growing and knowing is.

And this goes out to especcially the newer grower: Don’t trust any opinion on the internet. Make your own Experience, before trusting too much nonsense, maybe the Grower could have saved a lot of Money and time by just trusting his own believes.

(I feel you Thierry. ;))

Be well everybody. I hope you can take it with a smile.

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Doh i even had that issue many moons ago but completely forgot about it. A cheap aquarium air stone, it was blue in colour and left blue granules in the res lol

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@Illyssian, so, it was partly the air pump. The air pushing through the stone fed minerals into the water. I knew something had to be getting added in from the air source. BTW, my answer in my first response (read it again) said the air pump was feeding calcium or lime into the water. The only dofference is the minerals weren’t in the pump but after it in the air line. Had you mentioned he was using an air stone, none of us would have been stumped.That was a sadistic game. Your suggested solutions were all misleading and you left out a vital piece of information. You should have given us 0 (zero) hints and just asked for opinions. :frowning:

@anon32470837, yes they can, but to you are missing the argument I’ve been making, aside from possible outgassing, none of your alternatives is going to continually change the pH, bringing it back to the same reading. Any minerals in the water have already made the pH difference. Something HAD to begetting continually added to the water to do that.

Edit: made additional comment.