Raising Mg and Ca in Reef Tank

Lisa007 · Mar 23, 2023

Hello!

I’ve had my 60 gal saltwater tank now for almost 3 years. I have a few random fish, and just recently am trying to take care of corals. These are my levels:

.02 phosphates
360 ppm Ca
1140 ppm Mg
12 dKH
.2 ppm Nitrates
Ph is at 8.2

I use Salifert test kits. So far, I have a frag of Zoas I got 3 days ago. They are open, but don’t seem at their full potential. I know my Mg and Ca are low, and Alk is high. What should I do? I get nervous about dosing, because I don’t want to mess up anything. But will if that’s necessary!

Randy Holmes-Farley · Mar 24, 2023

What is the salinity? I expect it is low and that is what is causing the low calcium and magnesium values (assuming they are accurate, which may not be true, especially for magnesium).

Testing your new salt water is also useful to know a variety of different things (test kit accuracy, salinity and water change effects, etc.)

Lisa007 · Mar 26, 2023

Randy Holmes-Farley said:
What is the salinity? I expect it is low and that is what is causing the low calcium and magnesium values (assuming they are accurate, which may not be true, especially for magnesium).

Testing your new salt water is also useful to know a variety of different things (test kit accuracy, salinity and water change effects, etc.)

Lisa007 · Mar 26, 2023

The salinity is 1.024, should it be at 1.026?

neonreef3d · Mar 26, 2023

1.025 is a good number in general.

gbroadbridge · Mar 26, 2023

Lisa007 said:
The salinity is 1.024, should it be at 1.026?

For coral, yes 1.026sg or 35ppt is the best place to be.

You will find most folks when quoting Alk, Ca, and Mg are assuming 1.026 as these elements are all related.

Which method are you using to check salinity?
You can make some simple calibration solutions to check the accuracy of your measurement which would be a good place to start.