i had a problem with my kalkwasser having a fishy smell to it. i figured out that it has something to do with my di water. when i used regular ro water without the di cartridge it smelled fine. the cartridge is supposed to change color when it is exhausted, but mine appeared to be fine. i have another on the way and hope this will take care of the problem. anyone have any idea why the di water makes the kalk smell funny?