It depedns upon your bio=load and what is being used up on a daily basis on what you need to add,that's why some people need to use a calcium reactor and some can get away with dripping kalk.16dkh is way to high I would stop adding the alk part of whatever you are adding to let things balance out.You need to keep testing and figure out what amounts works for YOUR tank,then go from there.Not everyone has the same bio-load so what the instructions say on the bottle will not work for everyones tank,some corals will take up more calcium than others,at the beginning it is kind of hard to get your tank dialed in because you need to test on a daily basis until you get the tank figured out.Once you get everything dialed in you will only need to test once every week or so,I test about once a week for ph,calcium and alk only I don't test for anything else.It can seem fustrating at first to get things just right but once you do it, it is usually smooth sailing from there and I also highly suggest you look into dripping kalk to maintaining your alk and calcium levels it makes life so much easier and it is cheap to do and easy.I hope this helps you out some as I sometimes have a hard time explaining myself in the written form.