Which Magnesium to use

[Randy Holmes-Farley Verified Community Expert]

FWIW, I sent this request to Brightwell Technical Service this morning so we'll see if they finally fix the description:

For many years now, you've had serious errors on your Magnesion P web site description, including the Guaranteed Analysis being way off. It simply cannot be 43% magnesium or have the magnesium boost per gram added that you claim based on the ingredients you add.

You use anhydrous magnesium chloride (25.5% magnesium) and anhydrous magnesium sulfate (20.2% magnesium). There is just no combination of these ingredients that can have more than 25.5% magnesium.

Especially since this is your guaranteed analysis, it would behoove you to fix this before people start asking for refunds. It will also save me the trouble of continually explaining to people online why you have such strange claims.

Thank you
Randy​

 

[Randy Holmes-Farley Verified Community Expert]

So I got a response from "Brightwell".

Apparently Jack Kent purchased Brightwell from Chris Brightwell in July and Jack has already removed the analysis from the page (and is reviewing the other data). Chris is no longer involved.

Seems like a good step forward.

 

[jsker]

Randy my last time to bother you until the next question. Mixing the two part. Volume of water 128 oz, 10 parts mg chloride, 1 part mg sulfate = 128 oz of water + 12.8 oz of mg chloride+1.28 oz of mg sulfate? or please send a link to the article and I will read.

 

[jsker]

So I got a response from "Brightwell".

Apparently Jack Kent purchased Brightwell from Chris Brightwell in July and Jack has already removed the analysis from the page (and is reviewing the other data). Chris is no longer involved.

Seems like a good step forward.

Nice follow up

 

[Randy Holmes-Farley Verified Community Expert]

Randy my last time to bother you until the next question. Mixing the two part. Volume of water 128 oz, 10 parts mg chloride, 1 part mg sulfate = 128 oz of water + 12.8 oz of mg chloride+1.28 oz of mg sulfate? or please send a link to the article and I will read.

Here's the article to make a recipe that can be used with various calculators:

Do-It-Yourself Magnesium Supplements for the Reef Aquarium by Randy Holmes-Farley - Reefkeeping.com
http://reefkeeping.com/issues/2006-07/rhf/index.php

http://reef.diesyst.com/chemcalc/chem_calc3.html

From it:

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.

Note that combining the two materials in solution can result in some precipitation of calcium sulfate (calcium and sulfate are impurities in the MAG flake and the Epsom salts, respectively. To assure yourself that the two materials have fully dissolved, dissolve each separately in some freshwater before combining them. Some calcium sulfate precipitation is acceptable, and it is okay to let the solids get into the aquarium, assuming you can dose in a way that prevents them from landing on delicate organisms.

Note also that this recipe (#3) is different from that given in my DIY two-part recipe, because in that case more magnesium sulfate is necessary to offset the rise in chloride that is provided by both the calcium chloride and the magnesium chloride

 

[jsker]

Here's the article to make a recipe that can be used with various calculators:

Do-It-Yourself Magnesium Supplements for the Reef Aquarium by Randy Holmes-Farley - Reefkeeping.com
http://reefkeeping.com/issues/2006-07/rhf/index.php

http://reef.diesyst.com/chemcalc/chem_calc3.html

From it:

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.

Note that combining the two materials in solution can result in some precipitation of calcium sulfate (calcium and sulfate are impurities in the MAG flake and the Epsom salts, respectively. To assure yourself that the two materials have fully dissolved, dissolve each separately in some freshwater before combining them. Some calcium sulfate precipitation is acceptable, and it is okay to let the solids get into the aquarium, assuming you can dose in a way that prevents them from landing on delicate organisms.

Note also that this recipe (#3) is different from that given in my DIY two-part recipe, because in that case more magnesium sulfate is necessary to offset the rise in chloride that is provided by both the calcium chloride and the magnesium chloride

You da Man, thank you again. Have a good day

 

[Randy Holmes-Farley Verified Community Expert]

You're welcome and thanks.

Happy Reefing.

 

[jaxteller007]

FWIW, it is not just the guaranteed analysis that is so far off, but the whole Brightwell description of how much it raises magnesium per gram added. Really poor product understanding.

I was given some Brightwell Mg and didn't think anything about adding it to my dosing container that already had some Seachem Mg in it. Yea those two do not mix lol. The Seachem turned kind of milky white and the Brightwell actually sat on top of it which was wild. When I drained it out (before any of it dosed into my tank thankfully), it mixed into a milky white substance. Thankfully I emptied it before any of that dosed into my tank. I'll not be mixing different brands of supplements in a container in the future that's for sure!

 

[jaxteller007]

Strike that, it was Kent Marine Mg that was already in my dosing container, not Seachem.

 

[Randy Holmes-Farley Verified Community Expert]

My guess one of them had some calcium in it and the other had sulfate, producing insoluble calcium sulfate.

 

[jaxteller007]

My guess one of them had some calcium in it and the other had sulfate, producing insoluble calcium sulfate.

Glad I didn't dose that lol. Ordered so Red Sea magnesium that should be delivered today.

 

[dannysreeftank]

I like brightwell products magnesium has a large option here https://amzn.to/2Y5hwIU

 

[Randy Holmes-Farley Verified Community Expert]

I like brightwell products magnesium has a large option here https://amzn.to/2Y5hwIU

Why do you like it? I really can't see a reason to prefer different magnesium supplements except by purity and price.

 

[dannysreeftank]

Why do you like it? I really can't see a reason to prefer different magnesium supplements except by purity and price.

The best reason would be I have no reason to not like it. It has never caused any negative effects for my tanks and comes in the two litters.

 

[diver22]

Hi guys, I have been doing weekly water changes and use Ocean Salt, seems that my Mag level just sits at 1160, Calcium is at 450 & Alkalinity is dKH 12.

Should I change salt to Ocean Crystal ? or should I dose Mag to bring the level up ?

And @Randy which one do you recommend buying ?

Thank you,

 

[Randy Holmes-Farley Verified Community Expert]

Hi guys, I have been doing weekly water changes and use Ocean Salt, seems that my Mag level just sits at 1160, Calcium is at 450 & Alkalinity is dKH 12.

Should I change salt to Ocean Crystal ? or should I dose Mag to bring the level up ?

And @Randy which one do you recommend buying ?

Thank you,

Do you mean Instant Ocean and Reef Crystals?

I used normal Instant Ocean for 20 years and think its a fine mix.

The low magnesium might be from low salinity or from a test error (which is common).

 

[diver22]

Do you mean Instant Ocean and Reef Crystals?

I used normal Instant Ocean for 20 years and think its a fine mix.

The low magnesium might be from low salinity or from a test error (which is common).

Instant Ocean is what I meant, and I use a Salinity Refractometer, and I keep it at a steady 1.025... I use Salifert Mag tester... I will test tomorrow again, first time I use it and could have been off a drop or so...lol I will get back to you on this...

Thanks.

 

[Randy Holmes-Farley Verified Community Expert]

Raising he salinity to 35 ppt (sg = 1.0264) will boost magnesium from 1160 ppm (assuming that is accurate) to 1225 ppm. I see no reason to not do that as a first step.

Beyond that, boosting it to about 1300 ppm seems like a fine plan.

 

[diver22]

Raising he salinity to 35 ppt (sg = 1.0264) will boost magnesium from 1160 ppm (assuming that is accurate) to 1225 ppm. I see no reason to not do that as a first step.

Beyond that, boosting it to about 1300 ppm seems like a fine plan.

Thank you Randy, going to try that first, and monitor for 1 month, if I need to dose a bit to get it up to 1300 what would you recommend.

 

[Randy Holmes-Farley Verified Community Expert]

Thank you Randy, going to try that first, and monitor for 1 month, if I need to dose a bit to get it up to 1300 what would you recommend.

A DIY is a fine way to go. Most hobby brands are also likely OK, but not necessarily better.

Do-It-Yourself Magnesium Supplements for the Reef Aquarium by Randy Holmes-Farley - Reefkeeping.com