Helping to take care of a friends pool. 20,000 Marcite sand filter. He recently bought the generic version of Kreepy Krawler. Shouldn't the hose be plugged in a port in the wall rather than where the vac hose fits inside the skimmer? There are three ports 2 or returns and the 3rd had a cap on it. When he took the cap off he said it was not a return port. So he plugged it into the hole the vac plugs into. Also can it stayed plugged in 24/7 and run on the same cycle the pump/filter runs on? Or should it only run a certain number of days and hours and let the filter run the opposite days and times????