magnesium for LPS?

[gusmanda]

The guys at my LFS said I need to add magnesium to my tank in order to succesfully keep LPS. Is this true? I don't see liveaquaria recommending this on the LPS page.

[papagimp]

Do not add anything to your tank that you do not test for. Magnesium included. When you mix up your new batch of saltwater before a water change, the mag levels should be where they are supposed to. And naturally these levels will decrease without proper water changes, but it sounds to me like your LFS wants to get more money from you. If you havn't tested magnesium, and found it to be low, do not add anything like that. If you mess up the magnesium levels, other levels in the tank will fall out of wack as well, and so forth and so on. You'll end up with a losing battle you don't want.

[gusmanda]

Right now I don't have any LPS, only a couple of softies. I also change about 7 gallons of water each week. Would it be reasonably safe for me to assume magnesium is OK for me to add a buble coral or a hammer coral?

[gusmanda]

By the way, I'm already aware I need to ensure proper CA levels are OK, as well as alkalinity, ph, phosphates, and nitrates/ammonia.

[bertoni]

Some tanks need magnesium supplementation. Others don't. That depends on the rate of water changes, the method of calcium alkalinity supplements (2-parts add magnesium), and the exact organism balance in the tank. I test magnesium every couple of months.

[J. Montgomery]

I add 1/4 cup of MAG flake (magnesium chloride hexahydrate) and 1Tb of Prestone Driveway Heat (calcium chloride, anhydrous) to every 5 gallons of salt water that I make (Tropic Marin salt + RO/DI water). Both calcium and magnesium run low in my salt make-up, so I boost them. Magnesium levels should be ~3x your calcium level. *By the way, you probably won't be able to find either of these products in Guadalajara since they're mostly used to melt ice.

If you look through the LPS forum, you'll see that calcium, alkalinity, and magnesium are frequently cited whenever people ask, "Whats wrong with my LPS coral?" All three parameters are related to each other in a balance. If you check the Reef Chemistry forum you'll find lots of articles related to Ca, Mg, and Alk.

Salifert sells good test kits for Ca, Mg, and Alk. I don't think that the LFS was trying to sell you something you don't need. Get a test kit and find out for yourself.

Like papagimp said, "Do not add anything to your tank that you do not test for."

[gusmanda]

OK, so it sounds like I'll have to buy a magnesium test kit to start with. I go to the US every six months or so, where do they sell the stuff that's used to melt ice?