Introduction

Calcium should be maintained between 380 to 450ppm. Calcium is important element in the reef aquarium as it is the building block in the formation of the skeletons and shells for many organisms.

For further information click on these links:
http://reefkeeping.com/issues/2006-07/rhf/index.php
http://reefkeeping.com/issues/2002-04/rhf/feature/index.php
http://www.advancedaquarist.com/issues/nov2002/chem.htm

You should check the magnesium level and make any adjustments before adjusting the calcium level.

Increasing your calcium level in your tank is fairly easy and can be done by using an "off the shelf" liquid additive. For small tanks/adjustments this can be effective, however for the larger tanks/adjustments then it is more cost effective to add Calcium Chloride.

If your calcium levels are high, then test a fresh salt mix to see what the calcium levels are, if unusually high then consider changing your salt brand. Carrying out regular water changes with a salt containing less calcium than your tank level, will gradually bring the calcium levels down. However Calcium is generally consumed in the tank over time by corals, algae etc. So unless the level is very high, it is normally best to carry on with your normal water change routine and wait for the calcium level to drop.

Application

Using the calculator below find out the dosage amount. Weigh the dosage carefully.

Mix the dose with 1 to 2 litres of RO water. Stir thoroughly to dissolve the salts until the mixture is clear. Then drip the mixture slowly over the course of several hours into a high flow area of the tank such as weir, sump return area etc.

Due to the sensitivity of marine organisms, it is not advisable to raise calcium by more than 20 ppm per day.

When increasing calcium, it is not advisable to perform other supplements at the same time.

If you are unsure about anything discussed above, raise a thread in the 'Help and advise' or 'Chemistry' areas of the forum.