Magnesium

[Gilbert]

Can someone please school me on MAGNESIUM. How important is it? what does it do/help? if i have a small tank (55gallon) and im dosing bi-onic should i worry about it? i was thinking about buying the Salifert test for magnesium but if its levels are high/low i wouldn't even know how to lower/raise the levels.

[rz1a]

It helps keep alk and calcium at higher levels.. usually when people report that theyve been adding calcium and it never elevates, it always has to do with the magnesium, unless test kit is bad. Usually people keep magnesium in the 1280 to 1300 range. You cant really lower levels unless they get depleted by your reef. I would only worry about magnesium if youre having problems with alk and calcium.. it's not dosed often as calcium or alk, but it is important

You can make your own, which is the cheapest, or you can buy some that are already made by Kent which is more expensive.

Elos is another good test kit, but it only tests by 100s.. like from 1200 to 1300, which isnt bad.

[Gilbert]

i have an API test kit and my alk usually reads low at 10 and my cal is in th e 600s, would that be because something is wrong with my magnesium

[rz1a]

Most likely youre dosing too much or your salt is just really high in alk and calcium. I think 10 dkh is great and i would keep it in the 9-10 dkh, it can get as low as 7 dkh and be okay, but I dont like to keep it there. Calcium should be in the 430-480 range, 600 is really high

you mentioned dosing b-ionic, doing this will raise calcium and alkalinity (if youre using both bottles). Dont follow the directions, just monitor your alk and calcium. If you have a reef that is really depleting both, then check every 3 days to see how your alk and calcium are and dose to the levels you want. There's a reef calculator on this board in order to find out how much to dose to bring it to a level you want. If it hasnt caused problems with your pumps or powerheads, I would leave it alone and stop dosing, or do a water change to bring it a little lower

If you dont have many corals or coralline that consume calcium, I wouldnt worry about it; youll probaby do fine with just doing water changes weekly

[rz1a]

http://reef.diesyst.com/flashcalc/flashcalc.html put in the amount of actual water volume you think you have: meaning the amount of water left after live rock and sand has displaced. I have a 75g tank and 20g sump, but I assume i have roughly 60 gallons total and it's a good number that I use to dose the two-part

[OrionN]

Gilbert,
Magnesium is not terribly important other than it interfere with the crystallization of CaCO3 thus allow us to keep Ca and Carbonate to be higher than saturated level in salt water. Natural sea water also has supersaturated level of Ca and Carbonate also not just in our aquarium.
This was how it was explained to me:
Mg precipitated on CaCO3 surface and coated it. This action prevent Ca and Carbonate ions form crystallizes on this surface thus get removed from the water. Without Mg interferences, Ca and Carbonate will crystallize out of solution at a much lower level.

[chark]

The best way to lower levels it with water changes and stop or cut back on the Bi-ionic. Here is a great article to read that explains sea water chemistry: http://www.reefkeeping.com/issues/2004-05/rhf/index.php