Dosing

[bkvreef]

What do you dose?
What would you suggest?
I presently have a 220g tank and a 55g sump
I have 3 brains (even though my wife will strongly disagree!)
numerous mushrooms
frog spawn
bubble coral
Just added xenia and a tiny amount of green star polyp.

[MechanicalEngineer]

I use the two-part (it's really a 3-part) solution.  I dose for alkalinity (baked baking soda), calcium (calcium chloride...ice melt stuff), and magnesium (magnesium sulfate (epsom salts) and magnesium chloride...MagFlake).   

It's very inexpensive and easy to make yourself.  Before you dose anything though, you should be testing to make sure you need to dose (and so that you don't overdose.)  Are you testing for Magnesium, Alkalinity, and Calcium?  If not, I highly recommend it, especially since you are keeping coral.  On the plus side for you though, it sounds like your coral load is fairly low on a 220g tank, so you shouldn't have to dose much, if at all if you're performing regular water changes.  How much water are you changing, and how often?

Here are some good links for you to read up on...and the recipe for DIY dosing:
http://www.advancedaquarist.com/issues/april2004/chem.htm
http://reefkeeping.com/issues/2006-02/rhf/index.php
http://reef.diesyst.com/flashcalc/flashcalc.html

[Logzor]

If you have a low demand system the best thing you can do is set up an auto-top off with saturated limewater. This will have you set until you start introducing large amounts of stony corals. You can buy Mrs. Wages Pickling Lime at Krogers, mix in two teaspoons per gallon and wallah - ultra-cheap alk/calcium/magnesium supplement. Just be sure that your ATO does not suck up the slurry at the bottom. All of it will not dissolve and will cloud your tank if it gets sucked in.

I top off with limewater 24/7 along with dosing two part due to the demand in my system.

+1 on the three part system. You only really need to add the magnesium once every two weeks to a month, though.

This is all that you really need to dose. In fact it is an absolute must once you get more stony corals and water changes alone will not replenish your alk and calcium levels. I experiment with iodine, strontium, and potassium but I have no conclusive results yet.