I used to have a 1 gallon jug that had a piece of tubing attached to it (about 1 1/2" above the bottom), so that it wouldn't suck up the powder at the bottom. It worked pretty well, but you have to make sure that the drip is consistent and that it doesn't let too much water come out. You can cause fluctuations if the kalk isn't dripped at the right rate, but it is very effective and is cheap, two things that make it really good in my book.