Discus and Angelfish. I had a pair of angels 4 years ago, so no problems with theory, it's an odd situation. I bought a "pair" of discus about 6 weeks ago. Then acquired 4 angels. Discus spawn every week, angels a day later. NONE of the eggs have fertilised since I got any of the fish.
I have been using peat in the discus and 1 angel tank for 2 weeks, PH remains above 7.
Just started with RO yesterday in the discus tank only. PH is around 7 after changing 40 litres over 2 days. KH has dropped to 1 degree from 3, GH is around 4. I am using an API kit (I know some people hate them, I have never had a problem).
I have a TDS meter on order, but not here yet. I am at the point after 6 weeks where I feel like giving up already. I can't understand why NONE of the eggs from 3 pairs can be fertile when my water is not overly hard. Some of the info I have read is conflicting and some makes sense. I don't know what to try next if anything