I've boiled the rocks for 20 minutes changing the water once. I now have them soaking in RO water. I tested the ph before adding the rocks and it was 6.0 which is perfect, I think. (Chemistry is not my forte!) I tested my own well water and it came up at 6.6. I have a question about using my own well water as it would be oh-so-much cheaper. I have a homemade reservoir (plastic and feedbags filled with soil), plastic barrel for the well, a combo of copper and plastic pipe and the water is fed by two brooks. There are trout happily swimming in the reservoir which must say something for the purity of the water. However, it is subject to runoff. This means it gets discoloured quite often. With the ph at 6.6 could my well water be acceptable for my tanks or should I stick with the RO.