As your aquaponics system matures, your PH will start to drop off naturally, this is a good thing to a point. We strive to keep our systems between 6.8 and 7.0, a very small window indeed, but a good slot for the fish and plants overall. Our kit is mixed here by us with the finest minerals, so that nothing will hurt your fish plants or your ecosystem that you have worked so hard to build. It comes in 5 pound bags. This keeps things simple. We will give you full directions on use as well as help you as needed.