mag issue

[zeoleo]

hi i have 200 liter mixed every thing doing great until i discovered that my mag is very low about 980 , i used to use 2 part dosing and keep alk at 10 dkh and ca at 420 or so .
i got 200gram of magnesuimn sulfate powder from chemical store and added them slowly after few hours every thing looking sad clams bta gsp candy openbrain frogspawn and zoas closed and shows unhealthy signs so imoved them to new container with fresh salt water and yes they survived,
but why that happened?is it possible that powder contain ammonia or toxic stuff ? btw fish are happy and never shows any bad signs

 

[Kryptonian]

Most likely was just the quick parameter changes. I doubt anything toxic was present but everything slowly gets used to what is available. Mag is normally kept at 1350+ so if you're trying to transition from 980 all the way up, that's a big change for corals. You mention after a few hours everything looking upset. Probably just way too short of a time frame to correct a prolonged issue. Fish probably wouldn't be bothered by the change but corals can feel it.

I'd suggest correcting that low of a nutrient over the course of a week or more.

Does bring up a second question when the corals are fine in fresh mixed salt tho because fresh mixed is very likely going to have higher than 980 mag reading.

Whenever adding something to the tank, it just needs to be done very slowly and also can be beneficial to pre-mix small doses is fresh mixed water then added to tank. It takes time to dissolve into water.

 

[Randy Holmes-Farley Verified Community Expert]

hi i have 200 liter mixed every thing doing great until i discovered that my mag is very low about 980 , i used to use 2 part dosing and keep alk at 10 dkh and ca at 420 or so .
i got 200gram of magnesuimn sulfate powder from chemical store and added them slowly after few hours every thing looking sad clams bta gsp candy openbrain frogspawn and zoas closed and shows unhealthy signs so imoved them to new container with fresh salt water and yes they survived,
but why that happened?is it possible that powder contain ammonia or toxic stuff ? btw fish are happy and never shows any bad signs

I don't think 980 ppm magnesium is likely to be accurate.

Check the same kit on your new salt water.

 

[zeoleo]

I don't think 980 ppm magnesium is likely to be accurate.

Check the same kit on your new salt water.

New salt water was : brand kent, mag 1100 ca 390 kh 5 ,but any idea about what's happened?

 

[Randy Holmes-Farley Verified Community Expert]

New salt water was : brand kent, mag 1100 ca 390 kh 5 ,but any idea about what's happened?

Looks to me like either your salinity in both cases is very low, or the test is off. New salt water at 35 ppt will not be that low. That's why I suggested testing it.

magnesium under 1100 ppm can only be attained by very low salinity, or adding a lot of calcium and alk for a long time, with no magnesium additions. magnesium testing issues are very common.