[powerreef]

This is a great debate folks and it is nice to see how much research has been put into this subject. I have been keeping a SW aquariums for 19 years and am one of those that used to used Dolomite as a substraight. Now one thing to remember is in those days there was no choice and very little knowledge. Now with the knowledge available know and products I would choose not to use Dolomite. Thier are a number of reasons for this choice , but it boils down to not worth the risk. Thier have been many studies measuring the effect Magnesuim on aquaria, and it has been found that animals exposed to high mag concentrations in SW begin to show significant relaxation (ie: works as anaethesia) and prolonged expose causes mortallity in almost all species. In the oyster farming bussiness Magnesium concentrated SW is used as a shucking aid, as in it causes theoysters and clams to relax to the point to where even if you drenge them out of the water and drop them on the dock they are still wide open.

Another thing that scares me is the effect that Magnesium has on alk and cal. As i'm sure you know magnesium will slow the percipitation of cal.by attaching its ion to the carbonate ion of calcium carbonate. What effect would this have on calcium if it sat in a tank with such high levels of mag. carb.. Another thing to remember is in seawater, more than half of the carbonate ions present at any given point in time are ion-paired to magnesium, and this substantially reduces the free concentration of carbonate ions available to precipitate with calcium.

I geuss what i'm trying to say is that magnesuim at natural levels is good , but at high levels the fact that joins with other minerals and chemicals and produces biproducts is not good. it is also absorbed by most corals and rock in your tanks and can have problems thier to.

Put all that crap together and it say I'll spent the extra 200 on the right stuff. now i dont know if i have made any sence in my ramblings but take it for what its worth.

Mike