Calcium dropping very fast

[Ibrat82]

Hi guys

I seem to be having an issue with calcium dropping very fast in my tank.

I have a 100 gallon tank with 8 sps frags 2 lps frags.

Here’s my parameters

Salinity 1.026
Alk 8.8 dkh
Calcium 400
Magnesium 1350
Phosphate .01 ppm
Nitrate .2 ppm

Yesterday my calcium was 410 so I dosed calcium to boost to 425 then 24 hours later I tested and it’s 400!!! How would it drop so fast when I don’t have that many corals? I noticed I have a few specs of corraline algae growing but very small about 1-2mm in size. Can it be the corraline eating all the calcium??

 

[Crabs McJones]

Hi guys

I seem to be having an issue with calcium dropping very fast in my tank.

I have a 100 gallon tank with 8 sps frags 2 lps frags.

Here’s my parameters

Salinity 1.026
Alk 8.8 dkh
Calcium 400
Magnesium 1350
Phosphate .01 ppm
Nitrate .2 ppm

Yesterday my calcium was 410 so I dosed calcium to boost to 425 then 24 hours later I tested and it’s 400!!! How would it drop so fast when I don’t have that many corals? I noticed I have a few specs of corraline algae growing but very small about 1-2mm in size. Can it be the corraline eating all the calcium??

What kit are you using to test your levels?

 

[Ibrat82]

I only use salifert

What kit are you using to test your levels?

 

[Crabs McJones]

I only use salifert

Is your alk dropping as well?

 

[Ibrat82]

Nope

I have alk and calc dosing. My alk is stable at 8.8.

Is your alk dropping as well?

 

[Crabs McJones]

Nope

I have alk and calc dosing. My alk is stable at 8.8.

Hmmm that's unusual. Let's see if the expert can help us out. @Randy Holmes-Farley any ideas?

 

[MnFish1]

You can't really be sure that it dropped. The margin of error in the test is 10 mg/l. So your original calcium might have been 400 - meaning you dosed to 415 some was probably used up overnight - and the second measurement of 400 really could have been 410 - or - the Ca precipitated in the sand bed, etc. A change of 10 mg/l calcium doesn't lead to that much change in alkalinity (@Randy Holmes-Farley knows the equation - I cant remember) - so it could be precipitation.