My brother is buying a house with a intex pool with I think a sand filter. I'll get a pic today to help figure out what kind. There is one intake from the pool, one hose to waste, and one return back to the pool. There is a valve on the top with various positions, Filter, filter to waste, backwash, backwash to waste, there are a couple more I cant remember at the moment. Turning it will send water out the waste line but it is always clean. I have a feeling the sand may be channeled. Around the valve there are approx 6 bolts holding it on, there are approx 25 around the canister holding the two halvs together. To see inside would you remove the 6 bolts? Were going by there today and I wanted to help him get it filtering. If this description is too lame I'll have better info tonight to clarify things.