>Which mag and calcium boost do you use Greg?<
I use calcium chloride in the form of Dowflake or Peladow. I have a huge bucket or two from before Dow Chemical changed the process. The new process results in material that may have a bit more of the element bromine (in the form of bromide) in it. But for occasional boosts to calcium even the more recently produced stuff should be fine. Remember, bromine (the element) is a natural component of sea water, you just need to careful not to boost it's level to some really high, unnatural concentration.
I use a mix of magnesium chloride and magnesium sulfate to boost magnesium. The magnesium chloride came from a group buy that I managed several years ago from The Dead Sea Works company. I tested it for ammonia and it came up VERY low. This material is apparently about the same as the MAG flake stuff you can get in hardware stores, but you never know. If you purchase a bag of MAG flake you should try adding just a little bit to your tank first, and also make sure the stuff looks really clean in the bag and mixes up very clean. If you decide the stuff is good, then squirrel it all away.
The magnesium sulfate I use is from Epsom salts. I purchase it from the drug store in big bags. The stuff from the drug store is USP grade, so it should be safe for use in a tank. Again, I'd make sure it mixes up clean, and dose a small amount the first time you use it to check for adverse effects.