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Sparty00
03/22/2008, 06:59 PM
Quick question how low can calcium be before you start to lose corals?

Reason for my question currently on vacation, someone is watching my tank. Their testing is showing that my calcium level has dropped to 300-310.

I am going to have them add some supplements to try to bring it back up, however want to know how much risk is there if they cant get it up higher before I get back in a few days?

Thanks !!!

Percula9
03/22/2008, 11:33 PM
If the right amount of supplement is added it should be okay. It also depends on what kind of corals you have.

jdieck
03/23/2008, 04:09 AM
Calcification in corals depends not only on the level of calciumbut also on the level of carbonate alkalinity and PH also.
There is a combination of the three that can make aragonite dissolution become an issue. Here are some examples at the levels were the coral will no longer be able to calcify:

pH = 7.7
Calcium = 410 ppm
Alkalinity = 2.5 meq/L
In this case note the low PH


pH = 8.2
Calcium = 340 ppm
Alkalinity = 1.0 meq/L
In this case note the relative low level of calcium AND alkalinity.


So for calcium at 300 to 310 ppm you might have an issue if your PH is below 8.1 and your alkalinity is below 3 meq/lt

The good news is that calcium additives are very safe and usually the addition does not create a problem so instruct them to add calcium supplement. Use the calculator to determine how much to add, Try calculating going to a maximum of 400 ppm until you come back.
http://reef.diesyst.com/chemcalc/chem_calc3.html