pump to big?

Hi All. New to this pool forum.

I have a 15x30 AG pool (approx. 10,000 gal). with a 1.5hp pump and 225lb sand filter. I think my pump is oversized for the filter as I get fine dirt blown back into the pool..especially once I start it up after it being turned off (even if only for a minute or so to clean the basket).

Is there a way to tell what the appropriate sizing is? I've read on other pool forums (sorry) that some people with similar sized pools are only running about 1/2 to 3/4 hp pumps... but would these be enough to run the water through my 5 solar panels on my roof? It's a dilemma.

I'm finding lots of used filters on kijiji in Ottawa... should I consider running two filters in tandem (the second one would catch the fine stuff) and then I could by pass the second filter when I'm running through the roof panels? Just a though...don't know if that creats too much pressure or not..

Anyways..just looking for other people's thoughts.
Thanks!
Paul.