Elevated Magnesium

Oshanickreef · Mar 6, 2024

Hello,

I just ran my parameters and noticed very high magnesium and was wondering if this should be of concern? I realize my doser was left on for a few hours but have it off now. Everything seems fine…hopefully.

Salinity 36 ppt
Alkalinity 9.7
Calcium 430
Magnesium 1660
Nitrate 10
Phosphate .13
Temp 78

Should i worry about this or just let my auto water change bring it down slowly?

Randy Holmes-Farley · Mar 6, 2024

If you know that you overdosed it and it is not likely test error, then I'd let it come down by regular or possibly accelerated water changes with no dosing.

If snails are lethargic, I'd accelerate the water changes, since that seems a common claim with elevated magnesium. Any other new problem apparent in the tank may or may not be related and we can discuss.

Be wary of folks saying there's no problem with magnesium at that level since their own experience may very well be with test error as opposed to real elevated magnesium. Magnesium test error is very common.

GuppyHJD · Mar 16, 2024

Randy,
I test magnesium once a month. My last three tests (salifert) were 1500, 1590, 1650. I do not seem to have problems with snails. I am dosing BRS Two part and have not added Magnesium for several months.

Randy Holmes-Farley · Mar 17, 2024

GuppyHJD said:
Randy,
I test magnesium once a month. My last three tests (salifert) were 1500, 1590, 1650. I do not seem to have problems with snails. I am dosing BRS Two part and have not added Magnesium for several months.

If magnesium appears to rise 150 ppm in a month and you did not overdose it (or dose any) and that salinity did not rise a lot, then that is test error and is why I recommend RMM (dose mag based on calcium without mag testing).

GuppyHJD · Mar 18, 2024

Randy Holmes-Farley said:
If magnesium appears to rise 150 ppm in a month and you did not overdose it (or dose any) and that salinity did not rise a lot, then that is test error and is why I recommend RMM (dose mag based on calcium without mag testing).

Thank you Randy. I read up on RMM and will suspend testing of Magnesium. I do use ICP every two months so will just see what it shows.
The coraline algae has slowed - which does not make sense.