Big drop in pH

[RSidetrack]

Help - I have had a huge drop in pH - I am guessing from changing out my CO2 system with a fresh supply (DIY method). I had pH buffer in the tank which was working until last night when I changed the CO2 out. My pH went from 7.0 to 6.4. How do I get this back up to 7.0 safely (I do have live plants, still cycling, no fish) and maintain at 7.0?


I have been doing some reading and it seems that it would be okay to keep the pH at 6.4, is this true? As long as it doesn't fluctuate greatly? Having a DIY CO2 system makes that a little more difficult as every time I change it the pH could change depending on the amount of CO2 released into the water. Any recommended pH regulators? As it appears mine didn't work too well. Previously my output was 1 bubble per second, now I am at 3 bubbles per second with the fresh batch since I added more yeast to get more CO2 in there.


Thanks!

[emc7]

could change depending on the amount of CO2 released into the water

Yes, CO2 + H2O = carbonic acid, like in soft drinks. Seachem does sell a "pH support" chemical for planted tanks. I haven't tried it. The issue really isn't the 6.4,. its the fact that your pH is apparently not stable. pH raising is much easier than lowering. The main danger of using CO2 is the threat of pH "crash" when the "buffering capacity' of you water is "used up". You are wise to get it balanced before adding fish. Either a strict schedule of water changes (so you add buffering capacity with the tap water) or some added buffer is called for. You have time to experiment. I have used the seachem "regulators" but not with CO2. They do have phosphates which matters to planted tanks.

[RSidetrack]

Originally Posted by emc7

Yes, CO2 + H2O = carbonic acid, like in soft drinks. Seachem does sell a "pH support" chemical for planted tanks. I haven't tried it. The issue really isn't the 6.4,. its the fact that your pH is apparently not stable. pH raising is much easier than lowering. The main danger of using CO2 is the threat of pH "crash" when the "buffering capacity' of you water is "used up". You are wise to get it balanced before adding fish. Either a strict schedule of water changes (so you add buffering capacity with the tap water) or some added buffer is called for. You have time to experiment. I have used the seachem "regulators" but not with CO2. They do have phosphates which matters to planted tanks.

Okay, I will keep working with it and try to get it fully stabilized before I add fish - since it is cycling right now it is a good time - hopefully drastic pH changes won't affect the bio-filter.

So if I stabilize it and it is at 6.4 is that okay? As long as it doesn't change anymore? Or should I try to get it back up to 7.0 again?

[JustOneMore20]

Co2 changes your pH. That means its working. Changes in pH from carbonic acid aren't dangerous to the fish. Its changes in the KH/buffer that are dangerous. Carbonic acid doesn't change KH.

Do you have a KH test? (carbonate hardness) I'd be interested in what that is. Chances are its a good number and you have nothing to worry about.

One full point drop in pH means you have adequate co2 (30ppm). But sometimes your KH won't allow your pH to drop that low and you'll still have adequate co2.

[RSidetrack]

Originally Posted by JustOneMore20

Co2 changes your pH. That means its working. Changes in pH from carbonic acid aren't dangerous to the fish. Its changes in the KH/buffer that are dangerous. Carbonic acid doesn't change KH.

Do you have a KH test? (carbonate hardness) I'd be interested in what that is. Chances are its a good number and you have nothing to worry about.

One full point drop in pH means you have adequate co2 (30ppm). But sometimes your KH won't allow your pH to drop that low and you'll still have adequate co2.

My kH is hovering around 60-80

[emc7]

The tetras and cories would like 6.4. Guppys and mollies like it higher, but its not the really pH they need, its hardness. They like hard water or salt in the water.

[JustOneMore20]

So in degrees hardness, your KH is around 3-4ish, which is fine. You want a KH of atleast 3 to keep the pH stable (when you aren't adding anything to lower or raise the pH). As long as the KH stays the same, you should be fine with the pH being low from co2.

[RSidetrack]

Originally Posted by JustOneMore20

So in degrees hardness, your KH is around 3-4ish, which is fine. You want a KH of atleast 3 to keep the pH stable (when you aren't adding anything to lower or raise the pH). As long as the KH stays the same, you should be fine with the pH being low from co2.

Actually the test I ran today had a gH of 80 and a kH of 120 - is that fine?

[JustOneMore20]

Yep, still fine. Its higher, which is the way you'd want it to go.

I just wonder why it changed. Did you add anything to the water (like baking soda or something to harden it)? Or maybe checked it close to a water change (or the last time)?

[RSidetrack]

Originally Posted by JustOneMore20

Yep, still fine. Its higher, which is the way you'd want it to go.

I just wonder why it changed. Did you add anything to the water (like baking soda or something to harden it)? Or maybe checked it close to a water change (or the last time)?

I checked it right after a water change last time when my ammonia was over 8ppm and had to lower it.