Welcome to our forum.
My hot tub has four intake suction drains on the bottom sides of it. Only 3 of them are taking water in. I talked to the manufacturer and he said that may be normal as if one may be blocked, the others will take water in. It just didn't sound right to me. I don't want to burn up a pump or a motor because the other 3 drains are trying to compensate for the one that is not taking in any water.