ph difference

[ifixoldhouses]

I got a ph of 7.2 coming out of tap, after 24 hrs its 6.8, I have been doing a 50% w/c every day and filling it back up afterwards, also have a 1gph drip/overflow running, is this too much of a difference?

[Jhhnn]

I wouldn't think so. It's unusual for the pH to go down with aging, as de-gassing CO2 makes the pH go up...

Right after the water change, I'd suspect the tank pH would be ~7.0, not enough difference from 6.8 to affect the fish at all.

Or so it seems to me...

[ifixoldhouses]

When I had a carbon filter in my whole house filter, it stayed at 7.2, but I was worried about the lack of fluoride in our drinking water.

[jaykne]

I have a ph swing of .5 and fill my tanks back up with a python hose never even seems to bother them, I don't think I would go to much more than that though. I know someone that has a ph swing of 1 and he does it the same way as I do but his fish do look pretty stressed after large water changes, they perk right back up in about 20 min but wonder how it could affect them in the long term, getting stressed like that everyday?