Ok for clarification. All measurements I have taken were on the 29g holding tank, not my 55g.
The additive they use to get the pH so high is soda ash Na2CO3. The HCl I am adding is purely to offset this. Chlorine and Chloramine, if any, is taken care of by Prime, that I put in the holding tank.
I usually start Saturday night, or sometimes Friday night by filling the holding tank with cold tap water. I then add the Muriatic acid which brings the pH down to around 6.6
I can't measure pH above 8, because I am using API drip tests (uncalibrated... i know
) After an hour or so I add the gH booster. Curiously, the water never gets perfectly clear, which means not all the sulfates dissolve fully.
Once the water is in the tank, it is clear within the hour. Maybe the filter takes out the rest and slowly dissolves it over time...
Minsc, I think I will try filling the tank a few days earlier and monitoring pH, but as it is, I have a powerhead and an airstone in the tank for at least 18h before doing the water change. The pH does not seem to be coming down, but that is after acid and GH booster.
In a couple of weeks I will have some vacation that I will use ti do more experiments on this I think.