From info from another forum that one member BillyBuea, test test kits, API Alk, and Ca are very good, plus the price is right, except, on the Ca test kit the first bottle you add 10 drops, then to get to your color for the amount of Ca you is 1drop times 20of bottle B, so if your Ca is 400 you need 20 drops to get there, but here is the kicker, both bottles are the same size!!! I have emailed API about this and why not have bottle B twice as large, I got the stupid run around on it.