Any way to reduce Magnesium

[Randy Holmes-Farley]

Nope, it does not. The only thing I can attribute it to is the AF salt. There was a thread going around where a user was getting readings in the 1600s I think on freshly mixed salt. I'm going to be mixing some to use on my fish QT and will check it to see what it is.

Likely from the salt, yes.

Real demand for magnesium is very low, and many mixes have excess magnesium to start with.

 

[Randy Holmes-Farley]

I mean that's fine you can disagree, I'm saying because of my own personal experience that's all.

What did you observe with what sort of setup?

 

[andrew james]

Here is my observation search every thread related to problems with stn rtn on sps and the one thing most of them have in common is Aqua forest salt. I used it for a few months and during that time my mag spiked to over 1600 and I lost several well established colonies to stn. The salt was the only change i made. Since switching back to tropic marine and red sea my sps has rebounded.

 

[Anirban]

Pretty fast? Like 1-2 ppm per day.

Lol...yeah unless its not the only thing growing in the tank.
Just not getting it that how the system maintain Mg without dosing for months and when he has a daily consumption of 2 parts.....looks like his calcification does not depends on Mg...

 

[Anirban]

Here is my observation search every thread related to problems with stn rtn on sps and the one thing most of them have in common is Aqua forest salt. I used it for a few months and during that time my mag spiked to over 1600 and I lost several well established colonies to stn. The salt was the only change i made. Since switching back to tropic marine and red sea my sps has rebounded.

Although I trust your experience but I really dont believe the fact that the salt is only responsible. I think @Randy Holmes-Farley can tell us better if alone Mg over 1600 can kill SPS when other parameters including Alk and Ca are stable along with nutrient levels.

 

[andrew james]

Although I trust your experience but I really dont believe the fact that the salt is only responsible. I think @Randy Holmes-Farley can tell us better if alone Mg over 1600 can kill SPS when other parameters including Alk and Ca are stable along with nutrient levels.

I dont think its the high mag in the salt causing the issues i think its some unknown thats in the salt. High mag is just a pain i dont think it hurts anything

 

[Anirban]

I dont think its the high mag in the salt causing the issues i think its some unknown thats in the salt. High mag is just a pain i dont think it hurts anything

Yeah, that part I understand. That can be a possibility. But as far I know people already tried TRITON analysis with reef salt and probiotic salt. The reports say reef salt was high in Mg in 1500ppm range but probiotic salt was reported to have Mg in 1300 ppm range. Other than this nothing extraordinary in those which can hurt anything. So, possibly its the transition more accurately the way of transition which hurt more than the salt composition. I was trying to help a guy here who was reporting to have STN and his parameters were bouncing quite a lot. He thought the same. But once we started a more logical approach towards the issue the STN stopped and now he is happy with the parameters. Now, we will try to balance his dosing amounts to maintain the parameters stable.

 

[Randy Holmes-Farley]

Lol...yeah unless its not the only thing growing in the tank.
Just not getting it that how the system maintain Mg without dosing for months and when he has a daily consumption of 2 parts.....looks like his calcification does not depends on Mg...

The reason it works is because magnesium demand is very low (even into coralline), and many salt mixes have more than enough to offset it by water changes.

Coralline is certainly at the high end of corals with respect to magnesium incorporation relative to calcium and alkalinity, but it is not that high.

From the scientific literature, one can see that the percentage of magnesium in the skeleton of one species of coralline (Corallina pilulifera)is 4.4% by weight.

http://www.advancedaquarist.com/2003/10/chemistry

Thus, the expected consumption of coralline relative to alkalinity is roughly 4.4 ppm magnesium for each 2.7 dKH of alkalinity, or 1.6 ppm for each 1 dKH.

Consequently, if you wanted to drop magnesium from 1600 ppm to 1300 ppm by incorporation into skeletons of coralline algae (this species, at least), it would take something like 188 dKH of alkalinity to be added. That takes a long time in any tank.

And since typical corals use much less magnesium per unit of alkalinity (some incorporate 5-100 x less), the demand relative to alkalinity is often much less.

 

[Anirban]

The reason it works is because magnesium demand is very low (even into coralline), and many salt mixes have more than enough to offset it by water changes.

Coralline is certainly at the high end of corals with respect to magnesium incorporation relative to calcium and alkalinity, but it is not that high.

From the scientific literature, one can see that the percentage of magnesium in the skeleton of one species of coralline (Corallina pilulifera)is 4.4% by weight.

http://www.advancedaquarist.com/2003/10/chemistry

Thus, the expected consumption of coralline relative to alkalinity is roughly 4.4 ppm magnesium for each 2.7 dKH of alkalinity, or 1.6 ppm for each 1 dKH.

Consequently, if you wanted to drop magnesium from 1600 ppm to 1300 ppm by incorporation into skeletons of coralline algae (this species, at least), it would take something like 188 dKH of alkalinity to be added. That takes a long time in any tank.

And since typical corals use much less magnesium per unit of alkalinity (some incorporate 5-100 x less), the demand relative to alkalinity is often much less.

Thanks Randy for the detailed reply. I always appreciate the scientific logic you bring into the hobby.
I have one more question which is bouncing around these days. Few people are reporting that they have high Mg in their salt mix which they think is causing STN their SPS. I was just looking for related scientific article which can actually prove that kind of claim. Do you think that is actually possible if everything else fall in normal range.

 

[Randy Holmes-Farley]

Thanks Randy for the detailed reply. I always appreciate the scientific logic you bring into the hobby.
I have one more question which is bouncing around these days. Few people are reporting that they have high Mg in their salt mix which they think is causing STN their SPS. I was just looking for related scientific article which can actually prove that kind of claim. Do you think that is actually possible if everything else fall in normal range.

I'm skeptical because loads of people boost magnesium to 1600 + ppm to kill bryopsis and rarely report coral issues.

 

[Anirban]

I'm skeptical because loads of people boost magnesium to 1600 + ppm to kill bryopsis and rarely report coral issues.

Thanks again, me too because of the same reason. I was just trying to clear my head off that I was remembering it right.

 

[fmp47]

With my first Bryopsis attack I maintained Kent Magnesium at 1800 for about 4 weeks then let it drop naturally. It returned with a vengeance. Then I kept it at 2200 for about 6 weeks. At least 2 weeks after all visible Bryopsis was absent. Also battled an infestation of Derbesia at the same time API Marine Algaefix. Along with bid H2O2. Algae free in DT for about one month. The point is I only lost coral that was smothered with Debersia. I never had any problem with the elevated Mg++ levels

 

[Toe]

Help -
I had a faulty Mag tester kit (JBL) and ended up overdosing my tank with Mag. I got suspicious about the amount of Mag I was adding and got a friend to retest the water. But its too late my Mg reading is over the scale 1700ppm (red sea Mg pro tester).
What should I do? Just leave it or try and get it down.
I think water changes wouldn't make much difference with this amount of Mg. Using RedSea coral Pro Salt.

 

[Randy Holmes-Farley]

Help -
I had a faulty Mag tester kit (JBL) and ended up overdosing my tank with Mag. I got suspicious about the amount of Mag I was adding and got a friend to retest the water. But its too late my Mg reading is over the scale 1700ppm (red sea Mg pro tester).
What should I do? Just leave it or try and get it down.
I think water changes wouldn't make much difference with this amount of Mg. Using RedSea coral Pro Salt.

You should get the exact reading by using a second syringe of titrant and add the values together.

It may be testing error. The amount added would really need to be incredibly large and magnesium test error is common, especially with the kit you are using.

Water changes are the only way to reduce it. A 20% change with a mix having 1300 ppm will drop magnesium from 1700 to 1620 ppm.

 

[Toe]

Thanks for your prompt reply.
I am using 0.85ml of the titrant when I get the colour change (done the test three times). The test card supplied with the kit only goes up to 0.8ml titrant = 1600. So I am estimating the value at 1700.
I think the test is accurate as a friend uses a Salefert test with close readings to the Redsea kit.
I think that I put about 590g of Magnesium Chloride into my tank (I now know this was a big mistake).
Ok Ill do the water changes, however, the Redsea salt I use is a bit on the high side for mag (1350) so it will take a few changes to get it to desirable levels.

 

[Randy Holmes-Farley]

The Red Sea magnesium kit is not very reliable, apparently, but could be certainly be accurate in this case.

What tank volume are we talking about?

 

[Toe]

Total volume 500 Ltrs.

 

[Randy Holmes-Farley]

Assuming the product was dry solid magnesium chloride hexahydrate, the mag would only rise about 125 ppm, not explaining the possibility of 1700 ppm.

 

[Toe]

Yes it was dry solid magnesium chloride hexahydrate. Ok I'm going to live with it at the moment and do scheduled water changes and keep an eye on the other parameters. You comments were helpful, thanks from a newbie.

 

[Randy Holmes-Farley]

You’re welcome.
Happy Reefing!