Our donut only came with a garden hose driven (venturi?) vac... it did ok on the med sized stuff--larger stuff clogged it--algae residue, dirt, sand & road dust from our caliche road went right through it--and we don't have real good water pressure either. Another option is a PoolBuster. I heard about it on this forum from many who own them and are happy. It's perfect for a 18' donut. It was pricey compared to the price of the pool, but probably the best investment I've made. The pooldoc site (I'm not promoting here... just referring) sells a model that they claim is specifically for these type pools. I got mine about a month ago and I cannot believe all the gunk I have gotten out of the pool. Plus, no more hoses.

As for the fine stuff... after watching the silt and gunk go through the pump, cartridge filter, and back out the return, I don't think you'd catch a whole lot by rigging a vac to the pump unless you add a sock somewhere to catch the fine particles. Otherwise, as sugggested above, maybe disconnecting the return hose... you're going to loose some water that way though.

Lori