Randy Holmes Farley Magnesium Supplementation Warning

[bbyatv]

If you are using only part 3 of the Randy Holmes Farly dosing scheme to keep you magnesium up, please read the following article:

 

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

 

I do not use parts 1 or 2 as I have a calcium reactor and kalkwasser reactor. I do however add magnesium using part 3.

 

After reading this article, I found that the mix ratio for epsom salts to magnesium chloride is different if you are using parts 1 and 2 than if you are just dosing part 3 on its own.

 

The amount of epsom salts is way lower if you are only using part 3 without parts 1 and 2.

 

Hope this helps.

 

Bruce

Edited June 4, 2010 by bbyatv

[flowerseller]

Thanks Bruce.

I have experienced a similar conclusion by using the standard 123 part but only making 3.

I always made a lighter product instead but the findings here make me feel better.

I was using 5 MF to 1 ES.

It is recommended in this article to use 7 1/4 MF and 3/4 ES added to a 1g container with the rest taken up with rodi water. Mix each separate and combine.

[Origami]

Alternatively (and I practiced this for a long time), you can supplement magnesium using only magnesium chloride and ignore the magnesium sulfate (this is Randy's second "formula"). While the chloride-sulfate ionic balance is off, the effect is minimal and, with regular water changes, the impact on the ionic balance is low.

 

Here's what RHF writes in the article that's linked above:

 

The easiest way to use these supplements is to first make a solution in freshwater. Any of the three different recipes may be chosen, but the second and third are most useful for most aquarists.

 

1. Using Epsom salts only, dissolve 8 cups Epsom salts in one gallon of water, and use that to supplement magnesium in amounts determined by 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 the least preferred of the three, but can be acceptable if used for small amounts of supplementation, or if combined with at least 30% water changes per month. It is also a more reasonable choice if calcium chloride and sodium bicarbonate (baking soda) are used in large amounts to supplement calcium and alkalinity.

 

2. Using MAG flake only, dissolve 8 cups magnesium chloride hexahydrate 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 adequate, but not quite as balanced as #3 below. This choice is not a good way to go if calcium is supplemented by calcium chloride, because together they will force chloride excessively high.

 

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.

[Almon]

Right. According to Randy, there is a balance between sulfate and chloride.

 

If you are using Randys two part to add calcium, then you are using calcium chloride and you need to use more mag sulfate to be in balance, so the ratio of mag cloride to mag sulfate is 5:3.

 

If you are using Kalk which doesn't change the chloride/sulfate balance, then use 10:1 which is close to the natural balance found in seawater.

[Origami]

^^ It's good to remind people why we even consider this. Thanks Almon.

 

This is a good article for those who want to know the composition of average seawater:

 

http://reefkeeping.com/issues/2005-11/rhf/index.php

 

In it, you'll see the ionic composition of seawater. This composition is what's driving the "ionic balance" that we target. From the article:

 

Relative Composition of Seawater Ions (by weight)

 

In the graphic, you can see that, by far the dominant negative (-) ion (also known as an anion because it's attracted to an anode) is chloride (Cl-). Next up, though, is sulfate (SO4--). On the positive side, the dominant positive ion, or cation, is sodium (Na+), with magnesium (Mg++) next in line. It's the ratio (or balance) between the chloride (Cl-) and the sulfate (SO4--) that we're trying to maintain when we dose a mixture of Mag-flake (magnesium chloride, MgCl2) and Epsom salts (magnesium sulfate, MgSO4) to our tanks.

 

The reason the ratio changes depending upon your supplementation approach is as Almon stated above. When you dose calcium chloride (CaCl2), you're not only getting the calcium that you want, but also getting additional chloride ions. These ions begin to shift the chloride-sulfate ratio over toward chloride. That's why, when dosing the magnesium part, the formula is set up to restore this balance.