A million different opinions on this one. When I had my 90 set up I used kent Essential and Iodide regularly. I can't say for sure what the benefits were but I know my corals generally looked pretty good, can't say I saw any negative effects. Lots of different factors with my 180, but I have been unable to get my sps and zoanthids to grow like they did in my 90. I have not been dosing the 180. And if you want a frag Keith come and get one. No experience with Aqua Vitro, though I have used other Seachem products in the past and loved them. If I could afford to use the Reef Advantage Calcium all the time I would. Loved that product.