If you go with an I/G pump, remember that you will probably need a lower HP rating--they are usually full-rated, rather than uprated.

I have 20,000 gal (approx) in an AG pool, but I have solar panels as well. I only have a 1hp Hayward Superpump and a 200lb sand filter. It's a two-speed and I LOVE it. I run it on low-speed 99% of the time.

I DEFINITELY recommend 2 speed pumps. Plus, sand filters run better when they are running below capacity, well below capacity.

Mine is simple--there's a speed switch on the back of the motor--I don't even bother with remote speed switching.