dosing magnesium with kalk at same time
 

can i dose magnesium chloride, magnesium sulphate and calcium hydroxide all together in my ato? Or is the high PH going to precipitate the magnesium as magnesium hydroxide? I just finished converting a large water softener reservoir into my new ato tank :)

A reef tank doesn't consume magnesium nearly as quickly as calcium carbonate. I find occationally adding a little bit of magnesium salts to my water change water is all that I have to do to stay in the 1400ppm range. 1 cup once a month for a 300gal 'moderately' stocked system to be exact. So unless you're trying to run a zero water change system why not just add it that way?

I figured adding some to the ato when needed would be easiest, that way it would slowly enter the system, rather than a larger swing.

are you going through magnesium quickly?
i cant even remember the last time I needed to add some and mine stays constant between 1350-1400 it must be a year or so.

A quick search on RC revealed a thread from 2007 where someone asked the same question. One of the moderators answered by saying that the magnesium would likely precipitate out of solution if mixed in freshwater along with calcium hydroxide.

it's not that I am going through lots of magnesium presently, but I am planning on reducing the amount of water changes.....
thanks for the info from RC, when I pick up some more magnesium chloride I can mix the solutions and see how much precipitate forms before dumping any in the ato.