I switched from two part to calcium reactor a year ago. Dosing was fun, but I had to keep up on the gallon jugs monthly. With reactor, I have refilled media twice now and one bottle of c02. Tank looks and grows the same. One thing I have noticed though; my pump impellers do not cake up with calcium like they did while dosing. I say that because I dose at work and my impellers still seize up every few months. Same alk/cal levels both tanks. Go figure.