I work with ice machines in many different commercial settings and water filtration is an important part of reliable ice machine operation. In the past twenty years we have had an increased problem with "slime" growing in ice makers present in restaurants where they have yeast (Subways, beer brewers, and such) due to the use of filters that remove the chlorine from the water supply. If you can get a filter that does not remove the chlorine you are much further ahead in keeping your water supply clean and the advice about adding bleach to your holding tank and scrubbing it when it is slimy is good, but perhaps using a good filter at the faucet where you draw your water for drinking is better. If you do not want the chlorine taste in your water then that is a better way to go. Sunlight infiltrating your holding tank is also a huge problem in creating issues, although I wouldn't think that would be very common.