HELP! Dosing Red Sea Magnesium

[mmatspr]

Ok, Im stucked as well, I have a 200l system, tested Mg at 1200, want to go to 1350, so I should dose 224g? Is that correct? Wouldn’t that be too much for a single dose?

Thanks in advance!

 

[Randy Holmes-Farley Verified Community Expert]

Ok, Im stucked as well, I have a 200l system, tested Mg at 1200, want to go to 1350, so I should dose 224g? Is that correct? Wouldn’t that be too much for a single dose?

Thanks in advance!

150 ppm is too much at once , IMO.

Also, how are you measuring it? Magnesium testing is so inaccurate that I do not recommend it, at least both without careful controls such as matching the kit to icp or testing new salt water.

What is the salinity? Low salinity also leads to low magnesium.

 

[mmatspr]

150 ppm is too much at once , IMO.

Also, how are you measuring it? Magnesium testing is so inaccurate that I do not recommend it, at least both without careful controls such as matching the kit to icp or testing new salt water.

What is the salinity? Low salinity also leads to low magnesium.

I use Hannah and RedSea Magnesium pro test as a doubnle checker. Salinity is at 1.025.

 

[Randy Holmes-Farley Verified Community Expert]

I use Hannah and RedSea Magnesium pro test as a doubnle checker. Salinity is at 1.025.

Boosting the salinity to 35 ppt (sg = 1.0264) will boost magnesium from 1200 to 1267 ppm.

I would at least test your new salt water and see if you get the expected value. Those kit names do not ensure accuracy, IMO.

However it may be low, and raising salinity and/or dosing can be reasonable.

Bear in mind that magnesium will only be low if you added considerable calcium and alk over an extended period of time with no mag dosing. It is never used faster than about 1/10th of the calcium consumption rate.