Why are small insects not filtering out of your swimming pool?

If bugs are'nt filtering out of your pool and you have a filter, obviously your filter is'nt working. Hope this helped. Bugs will naturally swim away from a strong current that is drawing them to a certain point. If the bug is not drawn into either the skimmer or the main drain grate they will never get to the filter. Even then, they will get caught in the skimmer basket or the pump basket. The filter is not intended for catching the bugs - that is what leaf skimmers are for. If thebug is on the bottom of the pool you can then vac it up but still it will only go as far as the pump basket.