Looking for suggestions for sealing ceramic pool tile at the waterline. I live in Arizona and the hard water here stains tile quickly. I have spent houses using acid cleaners and bio def 300 and have the calcium off. Now how do I keep it off?
Hmmm. Sounds like a water chemistry issue. Your tile should be sealed by the glazing.... Get a GOOD test kit (DO NOT rely on your pool store for testing!) and look at the articles in Pool School on this website. Proper water chemistry will prevent the scaling you are getting.
Seasoned users of this site will ask you what your CSI is (Calcium Saturation Index). Get the test kit that most/all of us have (look at our signatures - and update yours if possible!).
Since AZ typically has a water supply with high TA, your best bet is to maintain your pool chemistry such that you maintain CSI per poolmath at the lower end of the range, this will keep the calcium scale from forming. Read the articles on How to lower TA in pool school. Make sure you have a good test kit so you can accurately measure your TA, CH, pH. Bio-Dex looks to be some sort of acid suspended in maybe soap? Using plain muriatic acid would probably do the same thing a lot cheaper.
Also, watch this video: Non-Recommended Chemicals and read this article: Recommended Pool Chemicals