PH at 5.2 Need Help

[metsfan421]

In my non-discus (mostly assorted tetras in it) 90 gallon planted tank my PH has gone down to 5.2. I have a PH meter on the tank which is supposed to kick on C02 when the PH hits a certain level (around 6.8) which it had done for the first year I had the tank running. I had let the tank sit without huge water changes for a few months and the PH level went down to under 6 and won't go back up. Even with doing a huge water change, the water's PH would go up to 6.6 and then within a few days it would be back below 6.0 again. My other tank which is a 75 gallon discus tank, which uses the same exact water does not have this problem, that water's PH will continue to go up over 6.8 in which time the PH meter will kick on the C02 in that tank to bring it down. I never had the problem of a huge drop in PH in this tank, ever. Two questions, what could be causing this in the 90 gallon tank it has a good amount of plants with 2-3 inches of eco complete substrate, a couple of red rust colored rocks (almost looks like petrified rocks), and a few other rocks I got from ADA last year. Nothing was added after the original tank setup that could cause the PH to drop. There is some driftwood in the tank as well, but again, this has been in since the start. Second question is, is there anything I can put in the tank or in the canister filter that can help permanently buffer the water to keep it around 6.8 and allow me to use the C02 again? Haven't used the C02 in over a month and half.

Thanks for your help!

[brewmaster15]

No idea as to whats causing the drop in pH.. but a trick I use here to keep the pH where I want it in certain tanks is to add some crush coral or oyster shells to the filter in a nylon bag or stocking. You will have to play around with the amount to use to achieve a certain pH...but once you do, its pretty stable..

hth,
al

[metsfan421]

Thanks Al, I'll try that and post my results.

[metsfan421]

So I went and got the crushed coral put it in two deep blue media bags (about 2-3 cups on crushed coral in each one) and almost immediately the PH jumped to about 6.9. Fearing it would go higher I turned on my C02. After about 3 hours with the C02 on, it dropped the tank to about 6.5. Which is where it is now, I turned off the C02 because I didn't want it to drop further (looking for C02 to kick on at about 6.7 or 6.8 and keep the tank between 6.6 - 6.7) and it has been staying at 6.5. I will check tomorrow AM again and see where it stands.

[khooyang]

I have similar problem with my old tank. That is my QT tank. I leave the water in after QT for 1 or 2 weeks, then change water out, and PP the whole tank. Now, after adding water and put in 2 discus as I am converting this QT tank to a breeding tank and I have another 4ft and that will be my other QT tank.

What happened was the PH keeps dropping to 6, in fact 5.8 using my PH meter as API can only detect till lowest 6. This makes me wonder what's wrong. Clean up all my Eheim filter media for possible left over food, sponge filters, and vacuum the whole tank. After adding water with PH 6.8 in a few hours time, back to 5.8 !!!

I just don't get why this happen? And, I think what we have in common is we did left water sit in the tank for a while. I am wondering if this is the old water that have any chemical effect on the tank?

I think I am going to add some crush coral to stabilise the PH. Also, will crush coral alter the hardness of discus breeding tank that supposedly soft? Of course, I will add the crush coral slowly without shocking the fish...

Any comment would be helpful. Thanks a lot.

[Altum Nut]

Sounds like a faulty solenoid on your regulator.
How many bubbles per. sec. are you running your C02?
Are you turning off your lights at night?
Years ago, my system failed because of the solenoid and found all my fish near dead. Poured in baking soda in addition to a large w/c...all fish back to life within 2 hours with no losses.

...Ralph

[limige]

I just about lost a tank full as well one time. stopped messing with co2 at that point.