This one has me stumped. I have an inground, vinyl liner pool. It has a main drain, 2 skimmers, and 2 returns. The sand filter has a port for skimmer/main drain lines on the suction side.
When I opened the pool, the water level was quite low. Starting up as I normally do (after filling), I have great suction on the skimmers (with full port) and no suction on the main drain (with full port). It also loses about
1/2" water daily. So I assume it is a leak in the main drain. I plug the main drain in the pool, and the leaking stops.
But....with the main drain plugged and the port on full skimmer, I no longer get suction on the skimmers. Nothing. If I unplug the main drain, I immediately get full skimmer suction, good flow, no bubbles, perfect. I now re-plug the drain and within 30 seconds the skimmer suction no longer works, even with the main drain plugged and the port on full skimmer.
What gives? What does the main drain being plugged have to do with the skimmer suction? TIA, Bob