I've been using it for most of my weekly water changes since last year, I love it, and so do my corals. I have an R/O unit that I use for top off water, but in my 30 gal cube I change 10% per week and no additives or costly testing each time you use additives. I check once a month as long as everything looks good, and ca is 400 to 450, dh is 11, ph is 8.2, all I have to do it add some R/O with the catalina as it is usually 1.027 specific gravity. Other then lugging a couple of boxes of the water (40 plus pounds each) its all good.