Calcium supplementation


New member
I was wondering how often you guys add calcium to your water. I just got a test kit , so ive been adding about a teaspoon and a half in freshwater for 60 gallons, and it doesnt seem to be raising that much. I have seen a little bit more coraline growth.

So i was wondering how often and how much do you put in.

Im taking a water samples to john and Im gonna have him test it with a salifert test kit, if the test kit proves mine wrong, Ill buy one.


New member
i usually just allow my salt mix to provide the CA level i need-- when the new tank is finished being set up, i'll be using a calcium reactor that a friend loaned me. :) i feel that it is easier to just do a weekly 10% water change on any tank smaller than 55g rather than upset the alk/ca balance by adding ca in.


New member
also, the amount that you dose into your tank depends on the amount of hard corals you have in the tank.


Premium Member
It depends on your uptake. If you are adding a lot of corals, it will increase.

Testing daily, you will not see that much of a difference because Ca drops at less obvious amount daily compared to alkalinity.

This is reason and use for alkalinity and Ca balancing.

What is your current alk level and ca level?

What are you dosing it maintaining the Ca?

You may be at a saturation point and may be driving your alkalinity down by overdosiing the Ca.

However, the coralline will come when all parameters are stable and the tank has been up for a while, 4-6mos min depending on maturation and stability. Within time, you will have coralline growing everwhere and it will be a pain, because it will grow on EVERYTHING.


New member
Also you might want to check your mag level. Mg acts as a buffer for calcium so if it's low it will be difficult to maintain or raise calcium.

Coraline seems to grow like crazy in my tank when the mg is above 1300ppm.


Premium Member
In response to "How Often", I add daily. The question as to amount can be addressed as others have said before, based on test. In my tanks I want to keep the Alk at a dKH of about 9-10 and the Ca at about 430-450. Fragaholic makes an excellent point; you need to check your Mg levels too. I use IO salt and "always" have to add additional Mg and Ca to a new batch.


Premium Member
Same here. I bring the levels up in my mixed water first, but also add alk and ca daily to my sump (I don't have a calcium reactor) using Randy's 2-Part formula. If you haven't done so already, check out the Reef Chemistry forum on this board for more helpful info, a ton of articles, and a handy-dandy calculator for figuring out how much of each you might need to add.