Hi, my Infinity edge pool has a negative edge on two sides. When the pump is running, one catch basin is about 3 inches lower then it should be and when the pump is off the water level raises back up 3 inches to the proper level. I have noticed the other catch basin on the opposite side has a lot of water in it when the pump is running so kind of the opposite problem on the other side. Could this be a check valve issue or what else should I look at to diagnose? Thank you!