Magnesium at 1660!

[Ocean’s Piece]

So I have always had high magnesium for some reason and I have always pushed it off because I never saw an issue with my corals. When i did my monthly test for mag, I realized it was at 1660 after a water change (1540 after). I use instant ocean purple bucket, but that’s besides the point because I’m switching off of water changes and switching to dosing next week. Could I just let these levels drop, then start dosing mg, dose it in much smaller doses until it’s right, or not even worry about it all

*Red Sea test kit

 

[Ocean’s Piece]

Bump

 

[PeterC99]

Have you ever validated the Mg level with another test kit or ICP water test?

 

[jdiefenbaugh]

I would make sure salinity is not above 35 ppt, and find another Mg test to double check. My bet is the Red Sea kit is wrong. If it's not, it shouldn't cause issues besides possibly slowing your snails down. People use to purposely raise Mg to ~1600 to try and kill off GHA, and I don't remember hearing any issues from it.

 

[Randy Holmes-Farley Verified Community Expert]

IMO, it is much more likely that there is a test error in magnesium or salinity than that normal IO at 35 ppt has magnesium that high. Magnesium is not going to rise on its own.

How large was the water change that purportedly dropped magnesium from 1660 ppm to 1540 ppm? It would need to be something like 30+% for that to happen.

 

[Ocean’s Piece]

Have you ever validated the Mg level with another test kit or ICP water test?

No, but I have measured it several times at 1300 ish. It's just been 1500+ the past few months and never questioned it too much.

IMO, it is much more likely that there is a test error in magnesium or salinity than that normal IO at 35 ppt has magnesium that high. Magnesium is not going to rise on its own.

How large was the water change that purportedly dropped magnesium from 1660 ppm to 1540 ppm? It would need to be something like 30+% for that to happen.

1540 ppm was before a 5 gallon water change on about 25 gallons of water volume. So it was 1660 a few hours after that water change.

 

[Ocean’s Piece]

another bump

 

[Randy Holmes-Farley Verified Community Expert]

Unless you had a bad batch in the past, or added a really massive amount of magnesium supplement, I think test error is most likely. Magnesium test issues are very common.

I almost suggest folks not bother measuring it. Too much error to benefit ratio.

 

[Ocean’s Piece]

Unless you had a bad batch in the past, or added a really massive amount of magnesium supplement, I think test error is most likely. Magnesium test issues are very common.

I almost suggest folks not bother measuring it. Too much error to benefit ratio.

So you would suggest just dosing enough to raise it 120 ppm (rate of consumption per week) and keep it at the level it’s at?

 

[Randy Holmes-Farley Verified Community Expert]

So you would suggest just dosing enough to raise it 120 ppm (rate of consumption per week) and keep it at the level it’s at?

The rate of consumption of magnesium in a week cannot be more than a few ppm. It is not ever 100 + ppm.

It is not more than about 1/10th of the calcium consumption.

I'd add nothing and assume it is fine.

 

[taricha]

Red Sea often gives high Mg values. I and many others use Salifert Mg test for that reason.

 

[Ocean’s Piece]

The rate of consumption of magnesium in a week cannot be more than a few ppm. It is not ever 100 + ppm.

It is not more than about 1/10th of the calcium consumption.

I'd add nothing and assume it is fine.

Coming back to this thread now that I’m staring to figure everything out. So I have seen on some other threads that people (yourself included) have recommended not dosing magnesium at all and letting water changes supplement magnesium (correct me if Im wrong, I may have interpreted it a different way). I plan to do occasional water changes, maybe a 20% water change every few months just for trace and other reasons (dosing trace elements as well). Do you think it’s a good idea to just dose Ca and Alk and let the occasional water changes supplement the mg?

 

[Spare time]

So I have always had high magnesium for some reason and I have always pushed it off because I never saw an issue with my corals. When i did my monthly test for mag, I realized it was at 1660 after a water change (1540 after). I use instant ocean purple bucket, but that’s besides the point because I’m switching off of water changes and switching to dosing next week. Could I just let these levels drop, then start dosing mg, dose it in much smaller doses until it’s right, or not even worry about it all

*Red Sea test kit

I wouldn't worry about it.

 

[Ocean’s Piece]

Bump