What do you all suggest to measure my calcium

[kyarnkid]

I have 10 blue legs and 5 scarlet reefs and 10 astrea snails. I know that they are cheap but, I was thinking about adding some calcium additives for them so they can grow.
What do you all suggest and how much does it usually run for?
Also what kinds of tests measure calcium?

 

[fshhub]

sea chem makes a couple of product, reef builder, reef plus and reef calciu(i think), i use the reef pack, it has a bottle of all 3 and is normally @10-15$, depending on your lication
for testing, i also use the seachem tester, it is a bit more difficult than some, but does work, just when you buy one, make double sure it says calcium test kit FOR saltwater on it, soem tests, you can use from fw, but the calcium is one that will nont work, in any i have tried