I use Kent's Kalkwasser. I mix one "good" tea spoon in a gallon of DO water. I rigged me up a rubber maid tank with a valve on it. I do this once a week, and crack the valve so it is just drip.................drip...............drip, well you get the idea. Only mix enuf for one dose, because I have been told that it will "Go Bad" Also, when you mix it, do your best to NOT introduce any air to the water, I have been told that is bad too.
I have seen a rise in the coraline after doing this. I have also been told to put some coraline in the current and it will send the spores around your tank. I dunno about that thou....