Answered
Why does the pump lose its prime when the vacuum is hooked up?
You probably have air leaking through either your vac hose and/or the valve that controls your vac line. You might try replacing the gaskets on your valve stems and try a new …vac hose. Also important to get the air pout of the hosing you are using to vac wuth before opening the vac line. The pump loosing its vacuum is definitely caused by a poor seal somewhere between the suction of the pump and the suction inlet of your vacuum equipment. In the case of an above ground installation, check all connections of the hose and your vacuum apparatus. In the case of an in ground installation, you could have a crack in the pipes from the pool inlet to the isolation valve close to the pump. To check this, make sure the water level of the pool is ABOVE the connection point where you attach your vacuum hose. Set the filter up for vacuum operation WITHOUT hooking up the vacuum hose. If the pump keeps it's prime, your pipes are probably O.K. Check your vacuum hose and apparatus. If you keep the water level higher than the suction connection in the pool, even if the connection is not 100%, the pump won't loose it's prime. (MORE)
