Purchased this system for my 100 gallon tank at work (my first foray in CO2) and was so impressed with it that I bought a second identical system for my tank at home. The setup was relatively easy with clear instructions. The PH controller works like a charm. Since I got it up and running the plants are growing like crazy, and I haven't had to adjust anything. It's expensive, but I feel it is well worth the money. I had an issue with my diffuser not functioning correctly initially on the first system, but the company sent me a replacement by priority mail immediately. Before the replacement arrived the diffuser started diffusing (probably a stuck check valve). Impressed with GLA.