the young ones are 1 years old, was 10, 2 died on saturday as I forgot to turn the filter valve back on after water change, then I had 90 % water change, than follow by 60% water change that night. average size around 5-6cm to tail.
110 L for young discus, 4 adults average 10cm, had them for more than 2 years in 140L tank. No adult discus has died.
I used buckets to change water, approx 8L per bucket with 1mL of aqua plus + discs buffer. I did put cycle in too.
adult tank has worse water quality due to didn't treat the driftwood (tested first few weeks at the flat with new drift wood), but there are not much shit, cos other fish ate it lol.
I am renting a room, so I don't think I can have aged tab water, I have stay at this flat since April, and only fish died of me accidentally overdoz of tea tree oil, and forgot to turn the valve back on.
If they have survive this long, I don't really think my method has any problem. and I do have about 5 years fish keeping experience. I just test the pH, its 6.6.