Mag

What depletes magnesium in a reef tank ?

 

Mainly anything that is trying to calcify. Your fish to a small extent as well.

 

Stony corals are the main culprits, although the amount used is very insignificant compared to cal and alk. Mag is mostly maintained to stabilize cal and alk; for example, if mag is low, dosing alk won't necessarily raise alk, but may, instead, lower cal by forcing it to precipitate out of the water, clogging pumps, filters, etc.

 

My Mag is at 1350. So I shouldn't need to test it every week should I?

 

I run my mag a little higher,around 1400/1440,so I only test about once a month and only need to add about once every two months as opposed to my cal and alk which I dose ca and alk as needed daily and test about every two to three days where as mag is needed but utilized less than the other two.Also,every tanks consumption load varies and this will dictate how often it should be tested.I would stay with weekly testing until you have a good feel for how much is being consumed and how often it needs to be added.

 

Coralline algae actually uses quite a bit as well, in addition to what Mr. Bill has outlined.

IMO, no need to test weekly. Unless you have had some sort of precipitation event, the level does not change quickly. Monthly Mg tests make more sense if you have a handle on things.

 

Was just about to say that! Coralline has the highest consumption rate I believe. Mine is a bit high at 1500 and im getting more coralline growth than I ever have.

 

My Mag ranges from 1400-1600 but is usually more like 1440-1520 and I have amazing coralline growth.

 

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