- Limewater and kalkwasser (KW) are one and the
same; a very strong calcium saturated liquid solution that is added to
reef tanks to replenish the calcium absorbed from the water by many marine
organisms.
- Ideal Alkalinity Recommended: 7-10 dKH
- Ideal pH Recommended for Calcification: 8.4-8.45
Calcium is one of THE most essential
elements in nature required by corals, crustaceans, mollusks, coraline
algae and certain other calcareous forms of macroalgae to grow. By extracting calcium from sea water, they use it to build their skeletal structures from calcium carbonate. Now, this is where alkalinity comes into play. Calcium alone is not enough, because the availability of carbonate mostly depends upon pH and alkalinity. Skeletal growth can still take place if alkalinity is high, and the calcium concentration is much lower than that of sea water. However, if both are low, these calcareous animals and plants do very poorly and little growth occurs. The bottom line is that calcium, carbonate, pH and alkalinity all relate to one another. To attain a thriving reef community, all of these elements apply, not just calcium by itself.
- Natural sea water has about 380 mg. of
calcium per liter in it (380 mg/L). By adding a simple kalkwasser solution
to an aquarium, this level can easily be maintained. The ideal calcium
concentration level to strive for is about 400 mg/L.
- There are many factors to consider when determining
how much KW to add to a reef tank. The size of the tank, and what types
of corals and marine life are maintained in it are just a couple. The calcium
demand in a tank can vary and fluctuate with new coral growth, or when
adding new live rock, corals and other calcareous critters, so you will
need to adjust dosage amounts and frequency when needed.
How to Prepare a Solution
- First of all, use caution when working
with any calcium compound in dry form, because they are somewhat caustic. You should not allow the dry powder to contact your skin, nor inhale it, and it should be kept out of reach of children!!
- A limewater/kalkwasser solution can be made by using a purified
fresh water source, such as RO/DI or distilled water, and adding either calcium hydroxide (Ca(HO)2), or calcium oxide (CaO). Calcium chloride can also be used, but this calcium compound requires an
additional step in buffering the solution with bicarbonate, which makes it a less desirable choice.
- Solution Mix: We have read to add anywhere from
1 teaspoon up 1 tablespoon of calcium hydroxide/oxide to 1 gallon of water,
but the well rounded 1 teaspoon equation is the amount suggested most often.
The preparation and mixing of a KW solution is very important. If too much carbon dioxide is allowed to enter the mix, it causes calcium carbonate to form, which appears as an undissolved white residue that settles to the bottom of the container. This cannot be used and will need to be removed from the solution and disposed of. Don't mix more than one gallon of solution at a time. Each time the container is opened and the solution is used, it gets exposed to more carbon dioxide, and more calcium is lost.
The suggestion of adding supplemental calcium additives to your KW solution may help maintain a more steady balance of the pH and dKH (carbonate hardness) in the aquarium. One such suggested additive is strontium chloride. If you find your pH and dKH levels are too high, one suggestion to help bring them down to normal levels is to use bottled seltzer water, believe it or not.
How to Add the Solution
- The introduction of a KW solution into an aquarium should be done slowly, never just dumped in, and there are several ways this can be accomplished.
- Through top-off water being added to the aquarium or sump to replace water evaporation.
- By means of using a slow drip doser. Auto-dosers or metering pumps can be purchased, or you can choose to make your own simple slow drip water top-off system set up. A doser is also a good way to introduce nutritional supplements or other reef additives, such as iodine.
- By using a calcium reactor.
