I am little bit confused. My IG pool has 5 return jets 4 blow out water but one sucks in water when I turn the valve to the main drain or partially to MD from the dual Skimmers.
If I fully turn the valve to MD then it almost sucks my hand in, luckily the hole is small and it just sucked the palm of my hand into it. When this occurred the pool pump started to loose prime momentarily. I'm assuming the MD at the bottom of the deep end is plugged? I'm unsure of the history since the pool came with the house.