So long kinda longish story so please bare with me. Last month I got a 10 gallon tank and cycled the tank. I slowly added in 6 glofish danios. Well after a few days one died, a few days later another died. I was doing some research and saw that keeping them in such a small tank was cruel since they are such active fish. So next thing I know I am at the store buying a 20g. I brought over as much substrate as I could including the filter and as much water as I could. Within a few days I lost another glofish and then another. I tested the water and the PH was 8.8+. When I bought the new aquarium I bought some new decorations so I promptly took them out thinking it could have been them? However, I suspected it was my water. I put some tap water in a bucket and tested it with a reading of 7.4, great. I then tested the water after 24 hours and it was at a 8.4. My tank water however the next night had lowered a bit to 8.2. At this point I am not sure what to do. I'm scared to change the water if that is that problem. However, I have also read fish like glofish can adjust to ph. I am not going to use chemicals to mess with the ph. We have well water which I am told is very hard. I read that driftwood and peat moss helps naturally lower the ph? I had a betta months ago too that mysterious got sick and died out of no where. As of last night my Ammonia level is at 0ppm, my Nitrites are at 0ppm, and my Nitrates are at 20ppm. I'm just getting really discouraged that I can not keep a fish alive no matter what I do.