I have a DIY CO2 and everything in the tank seams healthy. My PH is low at 6.0. The fish appear fine though, as do the plants. I was wondering if I should try to raise it and if I do, how should I do it? I want a more permanent fix, not a chemical one unless it is safe and fairly permanent. I was interested in crushed coral. If I use it, how much, and can I just pour it in the back of my tank where I wont be able to see it, being I have no room in my filter. I have a 20 gallon tank.