I have been treating one of my bettas for fin rot with nelafix for about 5 days. It has gotten even worse today. Ammonia, nitrite and nitrate are all 0. This is the tank that I where the pH had been dipping to around 6.0. I added crushed coral about 48 hours ago and the pH has risen to about 7.2. I wouldn't think that was too much to quick but maybe it is. He seems to be fine otherwise, swimming and even coming to bite my finger when I stick it in the water, thinking it's feeding time since he takes his betta bites from my finger. Should I take the crushed coral out? That would seem to just swing it back the otherway and be just as bad. Should I maybe try adding salt instead of the melafix? If so, is table salt ok and how much for a 2.5 gallon tank.