Use Kalkwasser as a slow drip to replace your total evaporation. It is chemically calcium hydroxide/calcium oxide, and is the very same product as pickling lime (Mrs. Wages or Ball pickling limes). Your goal is to make a saturated solution of calcium hydroxide using one to two tablespoons of lime to each gallon of RO/DI or equivalent water, placed in a closed container and agitated for 3 to 5 minutes to reach saturation. Upon settling for 10 minutes, this will end up with a solution that is a little milky at the bottom with a clear supernatant. Best to use the supernatant solution via a closed system (i.e., collapsing bag like an enteral feeding bag and set with a roller clamp to allow the solution to drip in over a few hours). The reason for leaving this sustem closed is that atmospheric carbon dioxide will react with calcium hydroxide to form calcium carbonate and water. The calcium carbonate is VERY insuluble in aqueous solutions (water based solutions), and will precipitate out a good deal of the calcium we are trying to put in the water column, making it unavailable to the corals. (You can see this readily by blowing your breath through a piece of air line immersed in the solution, it will immediately begin to turn milky white.) The ideal situation would be to use a
dosing pump to administer the approximate amount of replacement solution at the same rate of evaporation, but many aquarists find that they prefer to drip the total 24 hour replacement volume from 3 to 7 am, when the pH of the tank is at the lowest part of its daily cycle and will benefit the tank with its pH boost. I am not sure this is actually true (totally conjecture on my part), but as skeletalization does not occur at any significant levels during periods without photosynthesis, dosing at approximately 2 to 3 hours before the photoperiod starts should be the best time, as it has a chance for the calcium to reach the calcioblastic cells via transcellular diffusion and begin the calcification process, so that the "scaffold" built during the dark periods (calcification only) can then be completed with brick and mortar (the actual skeletalization of the building process) during periods of photosynthesis.
Even better would be to use a Nilsen Kalk reactor, but that is another story altogether. Might want to check
Bill-E's web page for the story on this process, I'm sure Bill would not mind the hits on his site. I am currently experimenting with the use of Bill's modifications with my own modifications to this unit to use it as an auto top-off system while still maintaining the slow drip necessary to prevent sudden shifts in pH.
[ 06-21-2001: Message edited by: tdwyatt ]
