MyR6Rocks
Aquarium Advice Activist
Ok, I've got a Small fortune wrapped into the 3 calcium test kits I own, and even by following the directions exactly with the same water sample my results are so far apart. My Salifert test reads 440, my Hanna Checker reads 488, and my API reads 400. I was told the "sweet spot" for optimal coralline growth should be as close to 440 as possible, but which one should I believe?