My feeders go 2 -3 weeks for sure even in summer. (if hummers dont get rid of it all first) I clean container well before filing. I use filtered tap water, bring it to a low boil, turn off the burner and add sugar. let cool of course before filling containers. I just dont get the mold hardly ever. I use water and white sugar only. no coloring etc.3 days would be the max. clean And refill.