Mag or Gag: Do you test magnesium?

[Reefing_addiction]

Black widows?

And yes! That is a real struggle. Mine struts around the tank like it owns the place (which it does). I'm hoping mine will start splitting soon.

Sherman’s
Luckily they stay on that side - more or less. Don’t wish for splits. When it starts it’s like a chain reaction. 1 gets 2 then 2 gets 4 ect ect next thing you know you have 16. Although my last round of splits got me one the size of a quarter!

 

[Reefing_addiction]

Why so much higher than the ocean? What do you think that level accomplishes?

A local reefer only test his magnesium when algae becomes an issue….once he brings it back to 1500+ no more algae problem

My tank

One time on an ICP test it was LOW like 1200 so i dosed it to raise it to 1450 and over shot. And I’ve just ignored it since. I do dose AF lab component (this is more recent - prior to the low mag reading) now.

 

[Dburr1014]

I do test but I admit, not very often.

I have seen it low when testing before and will bump it up.

Mag helps keep that ion balance. It helps stabilize the alk/calcium when it's kept in the 1300+ range.

I understand you don't need to test it often but not testing at all? IDK.
Argument from what I understand is water changes will keep it in range.

There was a wise man that said "don't add anything you can't test for". Does not testing mean don't add it? What if it's low and you don't know it? Just do a water change may not work all the time.

 

[Randy Holmes-Farley Verified Community Expert]

Hoping to keep bryopsis at bay with elevated mag

I’m not sure that is effective. Back in the day, not all brands seemed to work, leading to the possibility it was an impurity in the product used to raise it.

 

[Randy Holmes-Farley Verified Community Expert]

A local reefer only test his magnesium when algae becomes an issue….once he brings it back to 1500+ no more algae problem

My tank

One time on an ICP test it was LOW like 1200 so i dosed it to raise it to 1450 and over shot. And I’ve just ignored it since. I do dose AF lab component (this is more recent - prior to the low mag reading) now.

Have you tried normal magnesium levels to see if you get an algae problem?

I don’t think the answer to algae issues is that simple, or else no one would have such issues.

 

[BeanAnimal]

Algae is easy enough to grow... I assume a test would be rather straight forward (ignoring other side effects). Grow a 10 gal tank of algae and raise the mag to 1500 or so.

 

[Randy Holmes-Farley Verified Community Expert]

There was a wise man that said "don't add anything you can't test for". Does not testing mean don't add it? What if it's low and you don't know it? Just do a water change may not work all the time.

Curious that the same folks saying this still sometimes add things they cannot test for, such as vitamins, amino acids, organic carbon sources, bacteria, peptides (FM bolus dosing plan), many zeovit and other brand products of unknown composition, etc.

 

[Koty]

As I do no water changes, I do test Mg:
Primarily, I test Salinity with a hydrometer
then I take a triplicate of Red Sea and at least a duplicate with Hanna (Hanna gave a correct value when testing it with the Fauna Marine multi-standard)

 

[Randy Holmes-Farley Verified Community Expert]

Algae is easy enough to grow... I assume a test would be rather straight forward (ignoring other side effects). Grow a 10 gal tank of algae and raise the mag to 1500 or so.

Yes. I’ve never seen anyone try that.

 

[1112-425XL]

Not as often as Alk. PH, NO3, PO4, and Ca, but I do test Mg now and then.

 

[dakoop]

I test mine daily, but only because I run a Trident.

 

[boacvh]

My apex tests it but I never look at the level and I have never added anything in reaction to a measurement.

 

[Uncle99]

Sure, not often though.
Good piece of mind for me.

 

[Reefing_addiction]

Have you tried normal magnesium levels to see if you get an algae problem?

I don’t think the answer to algae issues is that simple, or else no one would have such issues.

My magnesium has always run high (according to ICP test) and even the Salifret test (when I did test). I don't really test it though. But when I do it was usually 1450 +. One of my ICP test came back with a reading of 1200, and then I had to dose to get it up. This was after a large addition of corals were added (maybe 2-3 weeks) and since my normal test results were in the 1450 range that's what I was aiming for when I dosed, but I overshot it. I cannot confirm or deny the use of mag in keeping algae away - but I have heard from more than 1 person that higher levels seem to help them. I don't really have an algae problem - and I didn't get one when my mag was low so who knows. My tank is happy with the mag levels so I'm not going to go messing with it.

 

[Randy Holmes-Farley Verified Community Expert]

My magnesium has always run high (according to ICP test) and even the Salifret test (when I did test). I don't really test it though. But when I do it was usually 1450 +. One of my ICP test came back with a reading of 1200, and then I had to dose to get it up. This was after a large addition of corals were added (maybe 2-3 weeks) and since my normal test results were in the 1450 range that's what I was aiming for when I dosed, but I overshot it.

Lots of people make the algae claim, but I’ve never seen any evidence to support such claims, except the bryopsis killing with Kent Tech M. I suspect other alga claims are misunderstandings based on that original data.

FWIW, I’m not surprised you over shot the magnesium because the 1200 ppm from 1450 ppm in 2-3 weeks was error or a salinity change. To loose 250 ppm of magnesium, you would have had to have consumed more than 2,500 ppm of calcium in that same time, which surely did not take place.

 

[Miami Reef]

Mag or gag is so funny.


Who even comes up with these titles? Please tell me @Gumbies R Us is involved. There’s no way someone can be this creative all by themselves.

 

[JulesH]

I took Randy's advice and stopped testing Mg. I see what the results are when I do an ICP test.

 

[KrisReef]

Magnesium testing...This is a hot topic in reefing! Some say you need to do it; others say it wastes time and resources. Where do you fall?

Do you test magnesium? Why or why not?

Want to know more about this topic? Check out this thread from @Randy Holmes-Farley - Just say NO to magnesium testing: RMM is born!

I have not tested my Mg in so long that I forgot that I bought a test kit to check it and now I have two.

I made the mistake twice at the same LFS, probably my favorite and so I am glad if I have to be so stupid that their shop could benefit from my lack of consciousness.

BTW: I find your pictograph of the three parameters highly offensive. NO3 should be brown, PO4 should be blue, and MgCL should be red. Don't ask me the pronouns, I think they all go by Thee?

 

[Reefing_addiction]

Lots of people make the algae claim, but I’ve never seen any evidence to support such claims, except the bryopsis killing with Kent Tech M. I suspect other alga claims are misunderstandings based on that original data.

FWIW, I’m not surprised you over shot the magnesium because the 1200 ppm from 1450 ppm in 2-3 weeks was error or a salinity change. To loose 250 ppm of magnesium, you would have had to have consumed more than 2,500 ppm of calcium in that same time, which surely did not take place.

Oh my calcium dropped as well as my alkalinity. It wasn’t just one it was all 3 lol calcium went from 480 to 330 ……alk went from 10 to 7.8.

Salinity is consistent- and I’m a no water change kind of person.

I’ve added an extremely large amount of corals in a very short period of time (I believe I’ve added 160 since February and 140 of those were between February and May - with the majority being LPS) .

 

[Randy Holmes-Farley Verified Community Expert]

Oh my calcium dropped as well as my alkalinity. It wasn’t just one it was all 3 lol calcium went from 480 to 330 ……alk went from 10 to 7.8.

Salinity is consistent- and I’m a no water change kind of person.

I’ve added an extremely large amount of corals in a very short period of time (I believe I’ve added 160 since February and 140 of those were between February and May - with the majority being LPS) .

Still, the mag drop was test error.