Lowering Mg level following Tech M treatment

[reefknight]

Trying to find out how to lower my Mg level? I've done four 20+ gallon water changes in four weeks on my 185gal and my Mg level is still 1620ppm. I haven't added any additional Mg since stopping the treatment.

I've had a few coral losses as well as several snails during this period. Trying to get things back to normal levels.

 

[jasin401]

following this...im guessing u raised mag to kill off bryopsis..which im currently trying to do with kent tech m treatment

 

[bertoni]

It'll take a lot of water changes. There's no other practical way to lower magnesium. What is the level of magnesium in some freshly-mixed saltwater?

 

[kgross]

Lots of water changes, and make sure your not using a high mag salt like Jonathan is asking you about.

 

[reefknight]

It'll take a lot of water changes. There's no other practical way to lower magnesium. What is the level of magnesium in some freshly-mixed saltwater?

:headwally: Didn't think to test the newly mixed saltwater. I'm using Red Sea Coral Pro, so if their spec's are correct it should be higher than average.

 

[kgross]

Yup, and that will make it take even longer for it to drop. Myself I don't think I would worry to much about the level, I have known people that ran 1600 ppm mag all the time without any issues. Not that I suggest that, but it does not seem to to cause to many problems once it is stable.

 

[BigKahuna]

I have the exact opposite problem where it takes tons of Mg supplements to raise mine and then it seems to get consumed fairly rapidly. What in my tank could consume so much?

 

[Randy Holmes-Farley]

Coralline is a reasonable consumer of magnesium, but if you are needing lots of supplements, that is more likely due to water changes with a low magnesium mix.

What salt mix are you using?

 

[BigKahuna]

I use Reef Crystals and I thought of that too. My last batch of prepared saltwater I tested, Salifert kit, came in around 1250 so not terrible. I have a decent amount of coraline but probably less than average, come to think of it my refuge has tons of it whereas my tank has something less because I have a significant amount of asterina stars which eat coraline AFAIK, the refuge doesn't seem to have any asterinas.

ETA- I don't really have a problem keeping Mg at nominal levels, just that when I try to raise it to inhibit bryopsis it takes a lot to get to 1800+ and then by the end of the week it is down below 1600 again.

 

[Randy Holmes-Farley]

Well, I'm certain your tank cannot use 200 ppm of magnesium in even a month, maybe not in a year.

That drop, if anything more than testing error (which is most likely), must be from water changes.

 

[Habib]

I use Reef Crystals and I thought of that too. My last batch of prepared saltwater I tested, Salifert kit, came in around 1250 so not terrible. I have a decent amount of coraline but probably less than average, come to think of it my refuge has tons of it whereas my tank has something less because I have a significant amount of asterina stars which eat coraline AFAIK, the refuge doesn't seem to have any asterinas.

ETA- I don't really have a problem keeping Mg at nominal levels, just that when I try to raise it to inhibit bryopsis it takes a lot to get to 1800+ and then by the end of the week it is down below 1600 again.

Well, I'm certain your tank cannot use 200 ppm of magnesium in even a month, maybe not in a year.

That drop, if anything more than testing error (which is most likely), must be from water changes.

Hmmmm..... unless.... just thinking.

If I understand it correctly there is only one (or a few) brand of magnesium supplement which seems to kill certain algae.

The metallochromic indicator can be blocked or it's performance hindered by certain heavy metals if in high enough concentration.

Perhaps it is a heavy metal contamination.

 

[BigKahuna]

I'd be inclined to agree with you but I've even tested it with multiple kits and am pretty anal in doing them exactly the same way every time so even if the testing is erroneous they are done as closely as I can make them. Even if the actual numbers are way off they should be able to detect the delta between them though right? That plus the fact that I seem to get about the expected ballpark of Reef Crystals @ 1250 or so would seem baseline is OK. I was using 2L of Magesnion over the last few months in my 75g and now moved on to 2L of Tech-M. I'd think if I overdosed things would be dead though? No dead snails and all the inverts and fish look happy and healthy. The bryopsis isn't dead but but seems to have slowed considerably. I'm just baffled how I could put through so much Mg supplement w/o any problems if I was in fact overdosing due to testing error.

 

[BigKahuna]

Hmmmm..... unless.... just thinking.

If I understand it correctly there is only one (or a few) brand of magnesium supplement which seems to kill certain algae.

The metallochromic indicator can be blocked or it's performance hindered by certain heavy metals if in high enough concentration.

Perhaps it is a heavy metal contamination.

Interesting idea. One thing I would say is that this tank has been up and running over 12 years and only the last few has it been a reef, before it was FOWLR and I never filtered top off or mix water and had nitrates and phosphate levels so high my test kits exploded. The last few years through perseverance I managed to get nitrates down to undetectable levels and po4 routinely under 0.05 0ppm, no mean feat considering my PO4 levels were probably over 10ppm of years as I did nothing to get rid of them. My substrate, crushed coral, is the same over the life of the tank and most of the rock has been there since the beginning with new additions along the way. I do wonder what contaminants I have acculmulated over the years. The question may be moot because the tank is going to be broken down in the next few months and the substrate at least won't be making the trip to the new tank. I have fish that are over 10 years old I believe, a blue regal tang and a couple of perculas, who have been I great shape the whole time so maybe I've just been lucky.

 

[Randy Holmes-Farley]

I'd be inclined to agree with you but I've even tested it with multiple kits and am pretty anal in doing them exactly the same way every time so even if the testing is erroneous they are done as closely as I can make them. Even if the actual numbers are way off they should be able to detect the delta between them though right? That plus the fact that I seem to get about the expected ballpark of Reef Crystals @ 1250 or so would seem baseline is OK. r.

No matter what you measured or what kits you used, there is just no possible way for magnesium to decline 200 ppm in a week. It truly never does nor can it even theoretically happen.

The only significant sink for magnesium in a reef tank is calcium carbonate that contains some magnesium.

In the usual proportions of magnesium to calcium in such a material with magnesium at the high end of normal, you'd likely need calcium to drop by 900 ppm and alkalinity to drop by 126 dKH. Obviously that cannot happen since neither is even present at those levels. Even pure magnesium carbonate precipitation would require an alkalinity drop of 47 dKH, which again is not even present in seawater.

 

[BigKahuna]

Is it possible for the Magnesion or whatever it is called was bad in some way? Because Iv'e put an awful lot of that stuff in the tank over the last few months and I see no negative affects, like dead snails or inverts. I top off with Kalk in my ATO and ALK runs around 170 ppm pretty consistently, CA is usually high 400's. Thanks for your replies - it just seems a mystery to me where my magical disappears to I have brand new Salifert Mg test kit coming - maybe I'll crack that one open and try again. Have you used that kit? Are you supposed to put in one level spoonful of the dry reagents into the vial?

 

[Randy Holmes-Farley]

It is not clear to me what negative effects one gets from magnesium elevation, nor what level it kicks in. There is very little useful data. It is not something scientists study very much since the ocean never has such issues.

Even the Tech M and bryopsis issue is likely unrelated to magnesium itself. That makes anyone's home data on magnesium negative effects suspect as to whether it is related to magnesium, or much more toxic impurities that are present at lower levels but still enough to be the first problem of overdosing.

I think it unlikely the Magnesion didn't have magnesium in it. It usually takes really large amounts of magnesium additives to raise the levels much. For comparison, a 100 gallon tank has more than a pound of magnesium in it, and even solid magnesium additives are often only about 10% magnesium by weight.

 

[BigKahuna]

Wow, 1 lb in 100gallons. Never really though about it like that.

 

[reefknight]

To clarify, I suspected the elevated level of Mg during the Tech M treatment as to the cause of my snails dying off. I do understand though that Tech M contains more than just magnesium. I was using a cause and effect diagnosis, not a chemist by any means. All of my other water chemistry remained within parameters.

I raised the Mg level from 1400ppm to 1850ppm over the course of a week and maintained that level for 30 days. At that point is when I noticed some inverts dying off. So I suspended the treatment and began lowering it again. I used both Elos and Salifert kits to evaluate the levels I was at.

 

[Randy Holmes-Farley]

Well, whether it is magnesium or another toxin, water changes are likely helpful, but may be slow.