I dose kalk once every 7-10 days or so. I mix up 4.5 gallons of water like I was doing a normal top-off. Let the water sit for an hour. Then I add about 4 teaspoons of kalk (that's the right amount for my tank), stir it up, cover it, and let it sit over night. In the morning I take the top off, and let it sit for 1-2 hours. I put the bucket on top of my tank and use small tubing (the stuff made to be used as an air hose) to siphon it into my tank. I make sure to add it right in front of one of my stonger powerheads. It takes about 1.5-2 hours to add the whole 4.5 gallons, and my fish never seem bothered by it.