Magnesium high

[dib]

I just tested with sailfert mag test kit and its somewhere over 1500 (that's where their chart ends) how do I lower it?
My calcium is low at 320 so I'm starting to dose liquid calcium to raise it up.
All other test results are normal, at least I think so.

PH - 8
Ammonia- 0
Nitrite- 0
Nitrate - 20
Phosphate - 0
Calcium- 320
KH - 9
Magnesium- 1520 ish
Salinity - 1.025

 

[Reefing Madness]

No need to worry. Its not at all out of bounds, and the tank will take care of it for you.

 

[dib]

Oh OK. I should still bring the calcium up to around 400 tho right

 

[Randy Holmes-Farley Verified Community Expert]

Yes, assuming you have confidence in the test. Is this a new tank? Low calcium and high magnesium do not usually go together in new salt water or very new tanks.

 

[eloehr]

I have the same problem or not a problem to an extent.

145g system - biweekly 25g water changes
SG 1.025 (reef crystals)
MG 1500
Ca 440
Alk 8.0

My tank uses .5 Alk daily but calcium never moves much. Why not? Tank is about a year old. It has about 25 sps frags and 5 LPS frags. I get growth, just no calcium usage. I've been waiting for MG to come down, but never does. Is it problem or "don't sweat it" or is it reef crystals? I've never tested a fresh batch of water. Guess I could.

 

[Randy Holmes-Farley Verified Community Expert]

0.5 dKH of alkalinity consumption will only be accompanied by a 3 ppm drop in calcium, so you likely just cannot detect that with a hobby kit amidst water changes messing with calcium levels.

At that rate of alkalinity depletion, magnesium will deplete less than 0.5 ppm per day. So you'll be waiting a long time to see the effect.

You have no problem that I can see.

 

[eloehr]

Thank you so much for being the expert that you are!!

0.5 dKH of alkalinity consumption will only be accompanied by a 3 ppm drop in calcium, so you likely just cannot detect that with a hobby kit amidst water changes messing with calcium levels.

At that rate of alkalinity depletion, magnesium will deplete less than 0.5 ppm per day. So you'll be waiting a long time to see the effect.

You have no problem that I can see.