High CA/MG Issues

WAfrican · Dec 13, 2015

Hi I've been having issues with high Calcium and Magnesium and need help. My ph stays stable around 8.2-8.3, alk is at 9, calcium is at 550, and magnesium is around 1700. The only thing that I dose is kalk at 1 tsp per gallon at around 1 gallon of evaporation a day. I have a 40 breeder setup with 30 long sump and currently use red sea coral pro doing a 10% weekly.

Randy Holmes-Farley · Dec 13, 2015

The only thing adding magnesium is your salt mix.

What salinity, and how are you measuring it?

WAfrican · Dec 13, 2015

salinity is at 1.026 and i use a refractometer that is calibrated.

Randy Holmes-Farley · Dec 13, 2015

The coral pro claims to have about 1450 ppm magnesium at that specific gravity. Unless you mixed up and used only a small portion of a container (which might have settled), I think it most likely the magnesium test is in error (which is very common).

Since it most likely (IMO) that it isn't that high, and if it was, the only way to lower it would be a water change but it must be coming from your salt mix, I wouldn't do anything special about it.

Calcium at 550 ppm is not high enough to warrant doing anything special about. Limewater (kalkwasser) use can very slowly boost calcium, and perhaps that is why yours is on the high end.

WAfrican · Dec 13, 2015

I will test my next batch of water after i mix it to see if this is the issue. The only issue i see is that I have used this test kit before on my tank and tested in the high 1300's. would there be this large of a range?

Randy Holmes-Farley · Dec 14, 2015

Yes, I've seen people find 1400 ppm one test then 1700 ppm a few days later, which is, of course, impossible. That said, it might be high if the mix is unusually high.

Downbeach · Dec 14, 2015

WAfrican said:
salinity is at 1.026 and i use a refractometer that is calibrated.

What do you use to calibrate, i.e. RO/DI or distilled water or a 35ppt solution.

WAfrican · Dec 14, 2015

Downbeach said:
What do you use to calibrate, i.e. RO/DI or distilled water or a 35ppt solution.

I use a 35ppt solution as required.

WAfrican · Dec 14, 2015

So i checked again today and i realized i may have used too much water the first time. I cleaned everything using vinegar and made sure to dry everything thoroughly and tested and got the following results. Alk-9, Calcium-520, Magnesium-1640. I'm starting to worry though because one of my acros showed signs of RTN. Could this be one of the causes?

WAfrican · Dec 17, 2015

I lowered my kalk dose as my alk was beginning to rise and my alk dropped to 7.4 from 9 over 3 days. What could be the cause? Should increase the kalk dose again back to where it was?

Randy Holmes-Farley · Dec 18, 2015

WAfrican said:
I lowered my kalk dose as my alk was beginning to rise and my alk dropped to 7.4 from 9 over 3 days. What could be the cause? Should increase the kalk dose again back to where it was?

Sounds like you perhaps lowered it too much. So I'd pick a dose in between.