Thanks for all the advice everyone, I really appreciate it. I am raising comet goldfish, they are inexpensive and fairly resilient. So what I am gathering from all of this is that I'm trying to hard to get everything right too fast. I changed out 60 gallons of water last night, my tank is 300 gallons. Should I add more fish? I only have 6 - 5" goldfish right now. The pH down I used I picked up at the hydroponics store and I was told it was safe for consumption and wouldn't hurt the fish, so I'm pretty confident that it's good stuff. I have 2 ways I check pH, I have an electronic tester that goes to 14 and it has never read higher than 8.0 then I test with my liquid test kit which has a low pH and a high pH test and it is between 7.7 and 8.0. I will be removing the oyster shells this morning, on my way out there in a minute. The new fish are doing very well so far. I will keep you posted. Real quick, the question I need answered right now is should I add more fish?