Mg media (use in CR) - Any recommendation

Hi,

Recently acquire a CR from a good bro. Would like to check if CR users has any recommendation of Mg media. I am now using the aquamedic Ca media that was given to me by the last owner.

I know that ARM Ca medium does supply mg but ARM primary function is to supply Ca, so I need a hard core Mg media to be use in my Cr. Read from the net that dolomite is the Mg media. Any brand to recommend?

My tank seems to be sucking alot of Mg. Mg would from frm 1300ppm to 1000ppm in a week or so.

Thanks alot - Rgds