Magnesium Sulphate

Cory · Feb 22, 2016

So MgSo4, will increase mag. And it will also increase sulphur.

Am i right when thinking it will add 1 part magnesium and 4 parts of sulphur?

Am i right when thinking about MgSo4 that when increasing 100ppm of tabk magnesium, that MgSo4 will also add 400ppm more sulphate?

JimWelsh · Feb 22, 2016

Pay attention to the molecular/atomic weights of the compound, and its constituent ions, and the ratios. Magnesium sulfate (ignoring water of hydration) has a molecular weight ("molar mass") of 120.365. Of that, the magnesium contributes an atomic weight of 24.305, and the sulfate ion contributes a molar mass of 96.06. So, the ratio of magnesium to sulfate is 24.305 / 96.06, which is very close to a 1:4 ratio. So, basically, the answer is, "Yes."

Randy Holmes-Farley · Feb 22, 2016

But not 4 parts sulfur, so looking at a Triton result which goes by sulfur and magnesium weight, it raises magnesium by 1.00 and sulfur by 1.32.

Cory · Feb 22, 2016

Ah ok. So 100ppm magnesium increase will also raise sulphur by 132ppm?

Also, if i never do water changes, wont sulphur and chloride from typical balanced mag supplements continually raise and become a problem?

Randy Holmes-Farley · Feb 22, 2016

Cory said:
Ah ok. So 100ppm magnesium increase will also raise sulphur by 132ppm?

Also, if i never do water changes, wont sulphur and chloride from typical balanced mag supplements continually raise and become a problem?

Yes, that is the boost, and no, they are not generally a problem because as they rise, they boost salinity, and when you correct for the salinity rise, they are back to normal.

Cory · Feb 22, 2016

Thats great then. Ive got some mg chloride clmjng in the mail. Been using epsom salts. Id guess id raised it 200ppm. So id have an extra 264ppm of sulphate in the water.

Currently my mag is at 1270ppm. I noticed my frogspawn a good indicator when mag gets low. It shrivels to a nub. After raising it, its recovering. Was at 1170. Seems it ddint like that level.

How much mg chloride should i add to balance out 200ppm mg increase from mg so4?

Randy Holmes-Farley · Feb 22, 2016

More than you can. My recommended ratio for a stand alone additive is about 10 parts of the chloride to 1 part of the sulfate.

That is because chloride is so much higher than sulfate in seawater.

Cory · Feb 22, 2016

Randy Holmes-Farley said:
More than you can. My recommended ratio for a stand alone additive is about 10 parts of the chloride to 1 part of the sulfate.

That is because chloride is so much higher than sulfate in seawater.

Wow! So if im thinking correct, id need to add 1800ppm of magnesium chloride to correct my magnesium sulphate additions? Maybe ill do a 80% water change and use a balanced mix after that.

Randy Holmes-Farley · Feb 23, 2016

Cory said:
Wow! So if im thinking correct, id need to add 1800ppm of magnesium chloride to correct my magnesium sulphate additions? Maybe ill do a 80% water change and use a balanced mix after that.

I wouldn't bother to do any special water changes just because sulfate is slightly elevated. I'd just stick to magnesium chloride for a while.

How are you supplementing calcium? If by calcium chloride, that is adding more chloride over time by far than is the magnesium additions.

Cory · Feb 23, 2016

Yes I used to use calcium chloride, but stopped a few weeks ago whwn i switched to just limewater. Ive added something like 150ppm total calcium chloride since the life of the tank. Ive only done 10 gallon water change in its life, total 28gallons. Shouldn't be as high then?

Could you get away with just calcium chloride, magnesium sulphate and baking soda to maintain the big three? Or does one eventually get too high?

Randy Holmes-Farley · Feb 23, 2016

Cory said:
Yes I used to use calcium chloride, but stopped a few weeks ago whwn i switched to just limewater. Ive added something like 150ppm total calcium chloride since the life of the tank. Ive only done 10 gallon water change in its life, total 28gallons. Shouldn't be as high then?

Could you get away with just calcium chloride, magnesium sulphate and baking soda to maintain the big three? Or does one eventually get too high?

That was the original recipe of my DIY two part (in 2002) and many people used it successfully, but when magnesium chloride became more widely available (via MAG flake), I added it to the recipe (in 2006) to reduce the increase in sulfate.

An Improved Do-it-Yourself Two-Part Calcium and Alkalinity Supplement System by Randy Holmes-Farley - Reefkeeping.com
http://reefkeeping.com/issues/2006-02/rhf/index.php

Aquarium Chemistry: A Homemade Two-Part Calcium And Alkalinity Additive System ? Advanced Aquarist | Aquarist Magazine and Blog
http://www.advancedaquarist.com/issues/april2004/chem.htm

Cory · Feb 27, 2016

So i got some mag flake, which looks delicious lol. Not the one you link in your article though. This is a bulk one though. Ive bumped it up to 1350mg now.

http://www.jlaquatics.com/shlobster-bulk-magnesium-chloride-flake-2500-gram.html

It says ammonia, bromine free, and po4 free. How long would you dose the chloride part, considering ive dosed 150ppm calcium chloride and 200ppm mag sulphate? Salt is io.

Randy Holmes-Farley · Feb 28, 2016

Cory said:
So i got some mag flake, which looks delicious lol. Not the one you link in your article though. This is a bulk one though. Ive bumped it up to 1350mg now.

http://www.jlaquatics.com/shlobster-bulk-magnesium-chloride-flake-2500-gram.html

It says ammonia, bromine free, and po4 free. How long would you dose the chloride part, considering ive dosed 150ppm calcium chloride and 200ppm mag sulphate? Salt is io.

Have you now stopped using the calcium chloride?

Cory · Feb 28, 2016

Yeah i have, i just use limewater now for convenience and stability. I should also add that ive added 30 g more of mag chloride. Ive also done 10gallons water change in its life.

Randy Holmes-Farley · Feb 29, 2016

OK, so going forward, I'd use a 10:1 mixture of chloride to sulfate, and at the moment I'd just use the chloride for a while (maybe the next 200 ppm magnesium) before using any of the sulfate. It's a little hard to specifiy since your water changes are likely reducing any imbalance , and I'm not sure where your salt mix starts anyway in terms of the ratio.