Ph keeps dropping, what am I not seeing? - The Planted Tank Forum
 
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post #1 of 5 (permalink) Old 02-04-2018, 10:59 PM Thread Starter
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Ph keeps dropping, what am I not seeing?

My tank has been up for about a month and so far everything has been going as expected. But over the past week my pH has been dropping out of the blue and I can't see a reason for it. After my water change yesterday my pH was 7.4 and now it has dropped to 7. Anyone have any ideas what is going on?

General Tank Specs:
3.5 gallon tank with Caribsea Floramax substrate. Not fully cycled yet, but ammonia has been zero for at least a week now. I did have a spike on 2/2 to .25 ppm, did a water change and its stable at 0 again so far.

Inhabitants are a betta and two nerites. (I know the two nerites are too much for the tank, I've been trying to get rid of one or both of them but the person I was going to give them to bought a snail eating fish and didn't tell me)

Nitrites have consistantly stayed under .25 ppm with water changes either every few days or when they hit .25 ppm
Nitrates have never gone higher than 5 ppm and are almost always under.
KH and GH have really only been tested once, they were about 4 dkh and 8 dgh a few weeks ago, KH looks like it has dropped to 2 dkh as of 1/29.

My tap water has a pH of about 8, and the KH/GH match my first water test. I started out using pH down, aiming for a pH of 7.2-7.4, but have decided thats silly and I have been trying to slowly raise the pH as I do water changes. The pH drops started just before I began reducing my use of pH Down.

Dosing a couple ml of Aqueon liquid fertilizer every now and then, about twice a week but no set schedule.

Oh and plants! Anubias frazeri, lobelia cardinalis (dwarf), dwarf hairgrass (i forget the scientific name) and a few El nino ferns that are desperately trying to reproduce before they die.

And here are the measurements I've taken over the past weekish:
1/24: pH 7.2 Ammonia 0 Nitrite 0 Post water change.
1/26: pH 6.6 Ammonia 0 Nitrite >.25
1/26: Ammonia 0 Nitrite 0. Post water change. Began reducing pH down usage
1/28: pH 7.2 Ammonia 0 Nitrite > .25 Nitrate > 5
1/28: pH 7.2 Ammonia 0 Nitrite 0 Nitrate ~0 Post water change. Fertilized
1/29: pH 6.8 Ammonia 0 Nitrite >.25 KH 2 dkh
1/31: pH 7.2 Ammonia <0? Nitrite .25 Nitrate >5
2/2: pH 7.0 Ammonia .25 Nitrite >.25
2/3: pH 7.4, others assumed zero Post water change. Fertilized
2/4: pH 7.0 Ammonia 0 Nitrite >.25


I know that KH is supposed to buffer against pH drops and that the drop in KH is likely related, but I can't figure out what is making either of them drop. Could it be the snails taking calcium out of the water?

Last edited by _mdc_; 02-04-2018 at 11:56 PM. Reason: typo
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post #2 of 5 (permalink) Old 02-05-2018, 02:05 AM
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Any product that changes pH has to overcome the buffering capacity of your water before it can actually change the pH. Also, the process that creates Nitrates also acidifies the water as a byproduct (this is what causes Old Tank Syndrome). This could definitely be the cause of your pH crash if you've stripped all the buffering capacity.

There is also the possibility that your water company includes an additive with your water to control the pH (regulations and all that) and these have the tendency to lose efficacy after a few days. Consider pouring a glass of tap water and testing it, then leaving it for a few days and testing again.

Having both nitrites and nitrates is worrisome - how much are you feeding? What type of filter are you using, and how often do you service it? If it's a cartridge system, do you throw them away at each service?

Is your substrate inert or is it designed to mess with water parameters? I'm not familiar with it.
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post #3 of 5 (permalink) Old 02-05-2018, 02:58 AM
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Donít use chemicals to buffer ph. The best ph is a stable ph, no matter what it is.

Just a noob


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post #4 of 5 (permalink) Old 02-05-2018, 03:33 AM Thread Starter
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Quote:
Originally Posted by BigMek View Post

Having both nitrites and nitrates is worrisome - how much are you feeding? What type of filter are you using, and how often do you service it? If it's a cartridge system, do you throw them away at each service?

Is your substrate inert or is it designed to mess with water parameters? I'm not familiar with it.
The filter is a TopFin Element I believe. It came with the tank and didn't come with much info. It is the type with vertical cartridges, I've cleaned the impeller once and that is it. I have not disposed of either of the two cartridges, especially since I haven't quite finished cycling yet and the filter has only been running a month or so. I'm feeding twice a day with 3-5 pellets each feeding. He eats them almost immediately, so they aren't polluting the water directly.

I believe the substrate is inert. I'll have to double check the bag to be sure, but I'm pretty sure I avoided a substrate that would mess with the pH.
[Edit Nope, it does say that it may raise pH.]

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Quote:
Originally Posted by Nlewis View Post
Don’t use chemicals to buffer ph. The best ph is a stable ph, no matter what it is.
I learned that after I started the tank. That would be why I am now working towards eliminating it from the water changes.
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post #5 of 5 (permalink) Old 02-05-2018, 06:57 AM
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As plants consume nutrients the water chemistry changes and this can easily cause the PH to go up or down. KH can neutralize acidic water but in the process this may reduce KH. Changes in CO2 levels also affect PH.
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