RHF 3-part DIY

dallasg · Jan 5, 2015

Hi Randy,

i am expanding my experience and knowledge on the DIY side of things, and would like to ask, on your 3-part formula for the Mg solution, can one only use magnesium chloride hexahydrate, or is epsom salts vital?

thanks

Randy Holmes-Farley · Jan 5, 2015

The Epsom salt helps keep the chloride from rising relative to the sulfate. Those are the two main negatively charged ions in seawater, and they are usually present in a fixed ratio in the ocean.

Exactly what may happen that is bad isn't clear (maybe not much), but since Epsom salt is generally available in an inexpensive and reasonably quality at a drug store (at least in the US), I'd suggest using it if you can find it.

Craig Bingman discusses it a bit here:

Aquarium Frontiers On-Line: Biochemistry of Aquaria

and

Aquarium Frontiers Biochemistry of Aquaria

dallasg · Jan 5, 2015

great thanks, its cheap here too..
why i ask, is after reading on the required water changes to alleviate the build up of sulphates, i havent done a water change in 4 years, and if i move to your 3 part i must factor in the cost of water changes
which is not all that much

Randy Holmes-Farley · Jan 5, 2015

I'm confused. My three part is designed to exactly not change the sulfate to chloride ratio, so no water changes are needed (at least not for that reason).

If you did not use Epsom salt, then I'd suggest water changes would be useful to help bring in some sulfate.

dallasg · Jan 5, 2015

At the end of the article you mention the need for water changes due to the build up of sulphates, and then refer to your article on water changes, or did i read wrong?

I will look when on my pc

Randy Holmes-Farley · Jan 5, 2015

Ah, now I understand.

I think maybe you are reading the older version which did use just Epsom salt and no magnesium chloride (since magnesium chloride was not readily available). Now it is available and the new (well, new in 2006) recipe is:

An Improved Do-it-Yourself Two-Part Calcium and Alkalinity Supplement System by Randy Holmes-Farley - Reefkeeping.com

This was the older (2004) recipe, that would build up sulfate:

Aquarium Chemistry: A Homemade Two-Part Calcium And Alkalinity Additive System ? Advanced Aquarist | Aquarist Magazine and Blog

dallasg · Jan 5, 2015

Awesome thanks

Randy Holmes-Farley · Jan 5, 2015

You're welcome.

Happy Reefing!

dallasg · Jan 7, 2015

sorry to be a pain in the ....

Recipe #1, Part 3A
Dissolve Epsom salts (3 cups) and magnesium chloride hexahydrate sold by the Dead Sea Works company (5 cups) in enough purified freshwater to make 1 gallon total volume.

is there a gram dose? or just measure 250ml or dry powder as a cup

thanks

Randy Holmes-Farley · Jan 7, 2015

Dry volume measuring is adequately accurate for the magnesium part as there are a lot of assumptions that go into determining exactly what it should be anyway.

But the recipe is intended to be about 64 ounces total, or 24 ounces of Epsom salt and 40 ounces of magnesium chloride hexahydrate.