need help have a 20x48 intex ultra frame upgraded to a sand filter from intex called the sandmaster pumps great at first but everyday having to backwash due to pressure readings and flow of water coming out im pretty sure im doing something wrong but cant understand intex helpline also when i try to vacuum i hook my hose directly to intake and the pump sucks air then evantually it will come back after i unplug for a few once i get that problem fixed i start vacuuming and i get about 2 or 3 swipes and my return coming back to pool is barley pumping what am i doing wrong my old filter would at least vaccum surley i dont need to backwash every 15mins when vaccuming please help :?: :grrrr: