Jason Scott explains whether a kalkwasser stirrer is needed as well as a calcium reactor on a reef aquarium.
For raising calcium, adding a product off the shelf is, in my experience, adequate and provides excellent results. In my shop we just check our calcium level weekly and add Seachem Reef Complete to maintain a steady 400-420 mg/l. This product also adds strontium and magnesium at the same ratio utilised by corals.
Even with all the corals in the shop they only use around 10-20 mg/l of calcium from our 6,820 l /1,500 gal system each week.
While there are situations where a calcium reactor is beneficial, I feel this is only required by the minority with large aquariums with rampant growth of SPS and LPS corals. They are not cheap, as you require not only the reactor, but CO2 system, bottle, regulator, for example, and ideally a pH controller and solenoid to regulate the pH in the reactor.
They can also quickly go through the CO2 so you don’t always save much money on calcium supplements. Even with a calcium reactor the level will still need frequent checking and adjustments made to the pH of the reactor, and flow rate through it to ensure calcium stay in the optimum range.
I prefer a supplement as it’s easier and means there is less equipment to check.
Kalkwasser, limewater or calcium hydroxide has to be used with caution as it has a pH of about 12! It should be added to the aquarium very slowly, as in dripped in through an air line. When kalkwasser is mixed it should be left to stand and just the clear liquid used.
We use a stirrer because if a small pump is used the high calcium level soon damages the pump, using an air pump causing the calcium to precipitate.
The stirrer has neither of these problems, as it is similar to a paint stirrer, but slower. A kalk stirrer is not necessary and the powder needs to be handled with care.
This item was first published in the September 2009 issue of Practical Fishkeeping magazine. It may not be reproduced without written permission.