I have 2 comet goldfish. One is older. I just got another recently. The older fish always was gasping for air and I discovered my ornaments were rising the PH really high overight, so I removed all the ornaments and the ph is stable now around 7. THe old fish is happy. But the new fish is lethargic. I tested the water this new fish came in and the ph is rather high. So, When I raise the ph of the tank for the new fish, the old fish gasp for air and opens his moth really wide all the time. I tried putting the old fish in a lower ph (temporary smaller) tank with PH 7 and then this old fish is ok. I do not know what to do. I have a 10 galon fish tank and a smaller 5 gallon temporary fish tank. I would like to have both comets together but the ph is a factor of stress. The paramenters are fine. I keep my Ammonia levels in zero or 0.25. Doing water changes everyday. I do have a whisper filter with carbon included. I had been battling with PH increase still but not overnight. It always will go up, no matter what, even know there is no ornaments. only the filter runing. I use well water treated by a softener only, so it is soft well water. I use a water conditioner that removed toxic heavy metals (as my well water does have heavy metals) the softener does not remove. I am using, just today a PH stabilizer product but it sems does not work with my water, initially PH 10. Marineland, PH regulator. I tried it today. The old fish is not lethargic. He looks happy, but my old fish is struggling already. I will move him to a smaller tank with pH 7 again by himself if he continues to struggle. It is the only way to keep him happy. Why having fish is so hard?. Someone help me please!!