I'm a bit lost at the moment, funnily enough probably because of reliance on plants and CO2 injection!
I have a heavily planted 200L community tank with CO2 injection controlled by a pH controller. There are four discus in it and one of them most probably has hex or spiro
I therefore set up an 80L tank to act as a hospital tank. Basically a bare tank with a heater, light, aeration and an internal power filter filled with biofilter sintered glass balls taken from the main tank.
I filled the hospital tank with 40L of water from the main tank and a 40L mix of RO and tap water in order to get a KH of 3-4.
Put the sick discus in it last night, dosed the meds per instructions. Today I checked the water parameters in the hospital tank: KH=3.5, GH=1, NH3/4=0, NO2=0, NO3=0. All fine and good (however the GH seems low but I think this is due to an older GH test reagent...) but the pH is at 7.85!
My main tank has a pH setting of 6.6 and varies during the day from 6.5 to 6.7 with water that also has a KH of 3.
So I assume that the hospital tank water, being aerated and very lightly populated (1 fish in 80 liters) has no CO2 at all and therefore pH went up...
I am so used to having just the pH I want by simply varying the amount of CO2 I inject that I've forgotton what to do in a case like this!!
So, how do I lower the pH in the hospital tank and keep it low (at least down to around 7). I guess I could put some peat in there but that is very slow and anyway not sure its a good idea with the meds in there. I could also do water changes with mixed RO/tap water to the desired pH but this would also get rid of the meds...
? Or just keep it as is at this pH?