I had been using Kent Marine Super Strontium & Molybdenum. After I ran out I switched to ESV's Strontium Chloride Solution. But I had much better results with the Kent's, so I may be switching back. Yeah those kits are expensive. I read the debates and most of the users of strontium were basically like ,use it for a while and you be the judge. So that's what I did. I felt it prudent to test if I was going to dose, and my strontium levels were never high in any tests. I was using the seachem test. If you think the test is expensive, the test itself is a royal pain in the...it take like 20 minutes using all kinds of different chemicals and you even get these rubber glove to wear because one of the chemicals can cause serious problems if it comes in contact with your skin.