Oh Kalkwater is a calcium additive. You buy it in powder form and mix it with your top off water it adds to your calcium, but it also adds to your PH and ALK.
So you have to add it slowly and preferably at night because the PH is lower with the lights off.
You need to mix it then wait for it to settle and then only add the clear liquid from the middle. I use a small tank with a hole about 2" up from the bottom and have a small piece of airline and a small valve so I can just drip it in at night.
IO is low on CA and MG to start with so you will have to top it up if you want corals or inverts.
There are other ways to add CA but I am partial to Kalkwater.

Just remember don't add anything you don't test for.:wink:

I am also partial to kalk. its been good to me in the past and its cheap.

Send me a PM if you want a bit to start yourself off, free, but you have to bring a container for yourself. If you want to do your Ca. another way, you can look at liquid additives as well. There are LOTS of brands for pretty much anything. Liquid though can be made expensive by adding water and charging based on weight.

Do you know what your Ca. and Alk. are at?

I forgot to mention. If you want to be cheap and not pay the price for the filter bags (some carbon products give them too you for free), you can use a pair of well washed nylons and make your own bag as big as you want.

Sorry to be the repeat poster...

I saw you were looking at the remora; here is a used one. http://canreef.com/vbulletin/showthread.php?t=41922