That really depends on your calcium usage which is dependent on your coral/clam stocking levels. If you have little, to no SPS, you do not need a calcium reactor. If your tank looks something like this:
Then a calcium reactor is probably recommended. (I don't actually have a calcium reactor on that tank though... I just dose Randy's Two Part sometimes. )
To calculate your calcium usage, see this thread:
Dosing for Alk, Mag, Calcium
Thanks... I've got no SPS, just softies, zoos and fishies. I'll do a search for the 2 part calcium additives. Anything in particular to use in terms of brands? I also need to find a good test kit, preferably one that tests for multiple things.
Is there any such test that will allow me to do Phosphate, Ca, Mg, Alk, Ph an all that other god stuff in one strip?