PH trouble

[dspeers]

I am curious, did changing to aged tap solve your issue?

[700dollarhat]

I’ve been doing water changes with about half RO and half tap water. I age it at least 24hrs and the discus seem to be happy. PH is 7.6 and I get the GH to about 6 with mixing tap and RO.

[dspeers]

Your gH is half of tap and now your kH is too. Below 3 you are more likely to have a rapid pH swing down as you have limited bicarb buffering. What confused me was your pH rising after being in your tank, made me wonder if you had something containing a salt that was dissolving and was a strong base and weak acid. Generally after subjecting tap to A RODI filter the pH will go down over hours as dissolving atmospheric CO2 lowers the ph. pH of pure distilled water exposed to atmosphere is ~ 5.8