Most use Kalk
to dose calcium and other additives as needed,, I have been using Oceans Blend which is a compilation of 70 trace elements as well as calcium and alk
supplement. It is an all in one 2 part solution. I add it everyday to my tank and have seen some great results, however, I will suggest that, if you choose to go this way, you will be adding more and more of trace elements that will not be used up and therefore require the use of carbon and regular water changes to keep the levels at bay. I am saying this because it causes debates and I don't want to start one..
I will let some of the Kalk
users comment on their usage now...