We have tons of pollen in NJ--they are saying this is the worst spring for allergies in many years. My sand filter works just fine on it.
I do use Al's DE strategy. A 10lb box should last all summer, even adding a cup each backwash.
While I don't personally use the "slime bag", it should work well. I do use skimmer socks and they pull a ton of junk out before it hits the filter.
Still, a filter problem sounds likely. Also see if you can determine if your pump is too big for the filter--that will cause problems and eventually damage the filter.
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