why is the holes inside of the filter isn’t socking in the bugs on top of the water in my 20″x48″ pool, it still have bugs on top of the water when the filter and pump is working. There is stains at the bottom of the pool, what can I do and use to get ride of it, its like a browish stain.

The proper water direction is needed from you return jets in order to force the surface contaminants, including bugs to the skimmer.