# Does Magnesium Cause Algae



## mistergreen (Dec 9, 2006)

Maybe it's the lack of other nutrients like NO3 or PO4. I have black/brown algae too but it seems to like to grow on slow growing plants and older bottom leaves.


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## plantbrain (Dec 15, 2003)

My tap has 51 mg/l of Mg, no algae issues here of note.

Regards, 
Tom Barr


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## csf (Jul 10, 2003)

Possibly you were short of Mg/Ca earlier and once you started dosing it, it threw the rest of the nutrients into a different balance - one where the algae thrived?

I dose about 9 tbsp of Epsom Salts MgSO4 every 4ish weeks (autodosing).



GIO590 said:


> My question to anyone here is does Magnesium in excess promote algae growth?
> 
> I have been battling a slow build up black algea (not shure exactly what it is http://www.plantedtank.net/forums/algae/50509-black-spots-56k-warning.html ) As part of the treatment I began dosing the tank with magnesium sulfate, while I waited to aquire the other chemicals. Following the magnesium dosing the black algea began to grow rapidly.
> 
> ...


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## Carissa (Aug 19, 2007)

I've never seen a difference between my tanks with anywhere between high magnesium and 0, as far as algae goes.


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