[Myka]

I really like the SeaChem Reef Advantage Calcium and Reef Builder (or Reef Buffer), however they are quite pricey compared to other options. The trouble dissolving the alkalinity powder is typical since it really just doesn't dissolve easily. Some brands are a sniff better than others, but all in all it will take some mixing. I use a MaxiJet 1200 to mix for about an hour when I make up new solution.

I also really like the Fauna Marin "balling salts". I switched from FM to BRS in the last year, and when I'm done using up my BRS chems I'm going to switch back to the FM as I found I had better results. I can't say for sure it was the chems causing the difference in my corals, but I can say my tank looked better while using the FM balling salts than it does using BRS chems.

You do not want to use epsom salts (magnesium sulfate) as primary magnesium supplement as your tank will get too high in sulfate. Magnesium should be supplied primarily by magnesium chloride with magnesium sulfate making up to 1 in 8-10 parts.

Also, you should be pre-mixing in RO, not tank water since mixing in tank water would cause precipitation with the calcium in the cup of water. That precipitation under normal circumstances is chemically bound which essentially ties up a portion of that newly added alkalinity supplement (and the calcium it stole) as useless. If you add alkalinity supplements too fast to the water you will see a white cloudiness or even flaking which is the precipitation I'm referring to.