I have an intex pool and purchased an intex sand filter and pump 1600 gph for my 18' foot pool last season. When I backwash the sandfilter, it states in the manual to then switch to the rinse cycle to settle the sand in the filter, or something like that. My question is when I switch to the rinse setting after backwashing, do I do this with the drain cap on or off. The manual doesn't specify if need to put the drain cap on after backwashing or after rinsing prior to switching back to filter mode. I'm new to this, and need clarification.