Jason, kalk and dosing both accomplish the same thing, they keep your Ca and alk at the levels your tank needs to be healthy. But if you don't have many lps or sps corals you may not need to do anything. Early in a tank's life just doing water changes will keep the Ca, alk and Mg up to healthy levels. When you start to see Ca and/or alk going down even with water changes, then you need to start adding Ca and alk either by kalk or dosing. IMHO dosing is easier and safer. My best guess is until you have a quite a few lps and sps corals you won't see much of a dip in Ca or alk. Especially if you do a 2 to 5 gallon water change every week or two.
I have a 50g cube DT with a 40g sump/refugium. It's full of zoas and anemones which really don't use much Ca or alk. I do have a couple of lps and a handful of sps corals along with a lot of snails, a flame scallop, a few feather dusters, an emerald crab and some porcelain crabs which do all use some Ca and alk to build skeleton or shell. So I test Ca and alk every Monday and usually need to dose about 30-50ml of Ca to get from 400 to 425 and roughly 50-75ml of alk to get from 7 to 9dKH. I don't use dosing pumps for an amount this small, I just dose by manually every Monday. Ca goes in the tank easy. Alk I have to feed in very slowly and right where a pump is moving a lot of water otherwise it will precipitate out. I get a little white cloud right in the area where I'm pouring it in, but the pump blows it out and it disappears as it is mixed with the tank water.
BTW, I use a sidewalk ice melting product called Dowflake to raise my Ca and swimming pool product (soda ash or sodium carbonate) to raise alk. You can also use sodium bicarbonate which is just ordinary baking soda. I used to have 4 tanks (600 gallons of saltwater) in the house before I downsized. So rather than buying Ca and alk products from an LFS or even Bulk Reef Supply, I bought serious bulk (25 and 50 pound bags) and very generic products instead. I used to go through a 50 pound bag of Dowflake in less than a year. It cost me less than $20. The same 50 pounds of Ca from BRS would cost me nearly $150. Yikes! And the savings in alk is almost the same. Oh, and after using these generic chemicals for over 10 years, no issues whatsoever! Randy Holmes Farley, in the R2R Chemistry Forum, was who recommended them back when he was on the other website. And most chemistry calculators will list Randy's Recipe along with all the other brand name Ca and alk additives.
