low PH won't come up!

[whitefire84]

HI all, I'm brand new here, so HI! *waves*
My situation is this - My tank had to be re-cycled about a month ago, due to stupidity on my part. It cycled fairly well, except that the pH went upto about 7.8 :O Not good. I waited to see if it would go down, which it started to, except that it didn't STOP going down. It's now below 6, which is as low as my water tester goes. I can't get it back up. I have tetras, which like the pH a little bit low, but it's getting excessive. My alkalinity is low, so I've been adding buffer for the past 2 weeks to get it up, hoping the pH would rise with it. A whole bottle of buffer later, and it (both the pH and alkalinity) haven't moved one iota. Any suggestions on how to change this? I'm running out of ideas. Thanks in advance.
-kristen

 

[Phlegethon]

What's the pH of the water from your tap, and how often do you perform partial water changes? My pH stays pretty stable with weekly water changes of 25%, sticking just slightly below the pH of my tap water.

I recently had to increase the alkalinity (KH) in my tanks though and I used a little bit (1.5 cup for a 40 gallon) of crushed coral placed in a media bag in my filter. The pH came up by 0.5 and so far has remained stable at that level over 2 weeks.

Do you have some major pieces of driftwood in there?

 

[jsoong]

HIya & welcome to AA!!!

What buffer are you using? What is the exact number for KH (alkalinity)?

For pH to swing & crash like that, you have to have almost zero in KH. This is not good for fish. To stabalize pH, you should have your KH up to something like 4dH or so. Best way to do that is to add carbonates. Baking soda can be used, others use crushed coral, or crushed oyster shell.

Also, what else is in your tank - driftwood? peat? plants?, and how often & how much water changes are you doing?

Anyway, to start with, we need the KH & GH of your (unaltered) water, then we can have a better idea of what to do next.

 

[whitefire84]

re: low pH

What's the pH of the water fro you tap, and how often do you perform partial water changes? My pH stays pretty stable with weekly water changes of 25%, sticking just slightly below the pH of my tap water.

I recently had to increase the alkalinity (KH) in my tanks though and I used a little bit (1.5 cup for a 40 gallon) of crushed coral placed in a media bag in my filter. The pH came up by 0.5 and so far has remained stable at that level.

Do you have some major pieces of driftwood in there?

*** My tapwater pH is exactly 7, and I perform partial water changes every two weeks. Hmm, didn't think of the coral. That I could try. I have a couple of seashells in there right now to try and bring it up. didn't do anything at all. And no, I don't have any driftwood in there, just aquarium decorations and plastic/silk plants.
-kristen

 

[Phlegethon]

That's odd. I don't know why it would be dropping that fast then unless you are injecting a lot of CO2...

 

[TankGirl]

Can you test your tap water after it has sat out for 24 hours? Sometimes it will be different, and you may find it is actually lower than 7 after sitting.

I am also curious as to how it got up to 7.8 before. Do you have any info about that - might give us some clues. Definitely need our detective caps on for this one

 

[Guest]

A test of your tap water's PH, KH and GH after standing for 24 hours is really needed to help out on this. If you don't have or can't get these test kits. Take a water sample to your LFS, most can test for these.

I agree that your tap might be lower than a PH of 7 after standing for 24hrs.

As for your PH swinging from below 6 to almost 8. Thats insane. Are your tetra's still alive? Most Tetra's generally tend to be a little sensitive. If your PH was swinging almost two whole points, most Tetra's (or any fish for that matter) would be dead. Are you sure your testing the PH correctly? Make sure you wash your test viels (SP??) good before and after testing water. Contamination can really throw off water testing.

An accurate measurement of your tap (let stand 24 hrs) and tank waters PH,KH and GH is really needed to help solve your problem.