Epsom salts are only Magnesium Sulphate
You're missing the Magnesium Chloride portion of the balance
You still need Magnesium Chloride Hex

Canreef member/vendor TimT sells Magnesium Chloride Hexahydrate
I just bought a 10Kg bag for $39

Jl aquatics just started selling bulk chems , Shlobster brand

Ok, looks like I've found this SafeStep locally. Any links on calculating dosage? Or how to add to 10:1 mixture to what amount of water change water, how often?

I personally find that adding 1 cup of 10:1 Mg salts to 15gal of water change water made with IO that I change weekly keeps my tank around 1400ppm. The reef chemistry calculator http://reef.diesyst.com/chemcalc/chemcalc.html works relatively well for calculating a starting point. This article might help too.


Do-It-Yourself Magnesium Supplements
for the Reef Aquarium
http://reefkeeping.com/issues/2006-07/rhf/

Brad, if it's M. C. Hexahydrate, you'll want to mix 5cups of it with 3cups Epsom salts into RO and after it's mostly dissolved top it up to 1 US gallon/3785ml
This will last you quite awhile, once your Mag is up where you want it

For dosing go to this Reef Chemistry Calculator and select Randy's Recipes 1 and 2 versions A and B
Don't miss the top window where you add your system volume if you want the calculator to actually work :wink:

Even though you have a Calcium Reactor, info on the Recipes is here;
An Improved Do-it-Yourself Two-Part Calcium and Alkalinity Supplement System
It'll tell you more about the Mag portion the Recipe

Edit: I didn't realise Randy wrote a separate article just for Mag
Thanks for the link

formula is different when you use calcium reactor.

I just looked into the 10:1 bit
I'm mixing mine 10:6 so there's definately a difference

Thanks. So 3 cups in a 50g water change is a good starting point? I guess if I'm going to dump stuff in my tank, I should read all the articles, right?? :)

I'm not using it in a reactor, just want to dump it in my water change batch. Easier that way.