2 Part Dosing

[hillegom]

When you get the mag chloride, get some mag sulphate (epsom salt) from costco. Its the cheapest. Mix as in the given recipe above.
Sorry, I don't know the difference betw. the powder and the flake.

[Myka]

Originally Posted by Randy Holmes-Farley

A certain mixture of magnesium chloride and magnesium sulfate has no net effect on seawater's major anions (chloride and sulfate). All that is necessary for such a recipe is to add these two ingredients in such a ratio that they add chloride and sulfate in the ratio naturally present in seawater (which is 7.1 to 1 on a weight basis and 9.6 to 1 on a per ion basis).

To perfect such a recipe, it's imperative to know the amounts of sulfate in Epsom salts (39%), the amount of chloride in magnesium chloride hexahydrate (34.9%), and their bulk densities, because most aquarists will use a volume based measurement (1.05 g/cm3 for Epsom salts and 0.85 g/cm3 for magnesium chloride hexahydrate solids). Taking all these factors into account, the desired volume ratio is 10:1, MAG flake to Epsom salts, as a supplement; for instance, 10 cups MAG flake and 1 cup Epsom salts.

http://reefkeeping.com/issues/2006-07/rhf/index.php

RHF wrote this article when calcium reactors were THE thing. 2-part dosing is more common now though, and we add a lot more chloride ions through calcium choride, so a better version for 2-part particularly if you are dosing calcium chloride heavily is 5:3 chloride to sulfate to make up for all the chloride we're adding via 2-part.

[hillegom]

I use this recipe from Randy Holmes:

3. Using both Epsom salts and MAG flake, dissolve 7¼ cups MAG flake and ¾ cup Epsom salts in one gallon of water, and use that to supplement magnesium in amounts determined using this linked online calculator, with the entry "Randy's Recipes 1 and 2 Versions A and B," and ignore for this purpose what those designations mean. This recipe is preferred, but its advantage over recipe #2 is minimal in most cases.

Which is derived from:
http://reefkeeping.com/issues/2006-07/rhf/

[reefwars]

which like mindy said is 10yrs old now

[reefwars]

oh and flake is most likely dihydrate fwiw

[Myka]

Originally Posted by reefwars

oh and flake is most likely dihydrate fwiw

Oh ya, that ^ too.

[Wretch]

What is the difference between hexahydrate and dihydrate?

[gregzz4]

Originally Posted by hillegom

I use this recipe from Randy Holmes:

3. Using both Epsom salts and MAG flake, dissolve 7¼ cups MAG flake and ¾ cup Epsom salts in one gallon of water

Deitmar, why are you using the recipe #1 Part 3B measurements ?
I use the Part 3A dosing with 5 cups and 3 cups

An Improved Do-it-Yourself Two-Part
Calcium and Alkalinity Supplement System

[hillegom]

I don't know Greg, I have been using that for a long time. Whats wrong with that recipe?

[hillegom]

ok, I looked up #1 3B
Thats not what I am using, that one is all epsom salts. (mag sulphate)
I use 7.25 cups mag chloride to .75 cups mag sulphate to one US gal.