Since most of the flowers are gone around our hives (winter is pretty much here) we've put our hive top feeders on and noticed that both our hives are doing very well with the extra food supply (1:1 sugar/water). However, we're constantly having to pull the feeders off to clean them. Mold seems to be a big problem.
My theory is that since it does get pretty warm during the day and the hives get a lot of direct sunlight this is a good environment for mold to grow inside the damp feeder.
The question is, once we get the feeders off and scrub them down with a brush (a clean dish brush that we never use for anything else) Is there a safe way to get the remaining mold out of the polystyrene? Especially in the corners is difficult to get and mold seems to flourish in those spots. We've taken an approach to not using any chemicals around our bees and want to know what an all natural cleaner would be to maybe soak the feeders. We definitely don't want to harm them in anyway so detergents or chemicals are things we'd like to avoid.
Thanks a bunch for any advice!