I have a fiberglass pool and question the returns near the steps. There is a return on both sides with a regular eyeball fitting. The eyeball fitting is only attached to the wall, the water comes out of a brass pipe about 3 inches from the pool wall. It appears there is a cavity that is full of water around the steps. There is also a vent on the top surface of the step that appears to allow air to be mixed the return when opened. I question this because I think I have a leak. Which all returns plugged water level doesn't drop, when pool is running water level dropped about 3 inches within a week and then stabilized, so I think it more of a shell leak vs. a plumbing leak. Could this water chamber around the stairs have a leak?