My tap water would measure around 7.4. Then after 24 hours filled into the tank it would be around 8.2. It is good swing on the PH. So far fish are doing fine over 2 months. I do daily WC 50% on 100g and sump as the filtration under my stand. The tank is in living room so I have no luxury on putting barrel in the living room. May be I can consider pickup a 30g and put it under the stand. Question here would 30g (aged water) mix with 20g (not age water) use to fill up 50g into 100g, would it ready help and make the big different for discus? I would think it may. Just want to throw out this question before I start implement it.