Dolomite in a reactor

[intruder]

I'm getting a calcium reactor and thought of using Dolomite along with the regular reactor media for the mag.part of it. There is a product called Ultra-mag for reactors. Anybody ever do this, are there more products,where could I find some. I didn't find any on two-part. The reactor will be a two-chamber if that makes a difference. Any comments ,suggestions are appreciated.
Thanks

 

[Randy Holmes-Farley]

Folks often put in about 10% dolomite. There are a few hobby brands, but they are not cheap.

for example:

http://www.aqua-medic.de/seawater/en/19/dolomite A/

 

[intruder]

Thanks Randy

 

[mflamb]

I use zeomag in my calcium reactor.

 

[Randy Holmes-Farley]

Thanks Randy

You're welcome.

Be sure to not try to boost magnesium that way, only to maintain it. If you boost it, alkalinity will rise too much. I discuss that here:

Magnesium in Reef Aquaria
http://www.advancedaquarist.com/issues/oct2003/chem.htm

from it:

It has been suggested that adding dolomite to CaCO3/CO2 reactors can help with magnesium problems. Dolomite is a material that contains both magnesium and calcium carbonate. If dolomite is being added to the reactor to maintain existing appropriate magnesium levels against the continual depletion via calcification (for example, if the calcium carbonate being used is too low in magnesium to maintain adequate magnesium) then this is a fine approach.

However, this method is unsuitable if the goal is to raise magnesium levels. The problem is that for every magnesium ion released from the dolomite, 2 units of alkalinity are also released:

MgCO3 ---> Mg++ + CO3--

Consequently, if one wants to raise magnesium by 100 ppm, the alkalinity will necessarily rise by 8.2 meq/L (23 dKH). The only way around this problem is to add a mineral acid (not vinegar) to the aquarium to reduce the alkalinity, and that may be more problematic than just adding magnesium in the first place.