The terminology can sometimes be confusing. The "aerator" pump brings water in from the lake...and if it is left on, it will bring water in and allow it to go back into lake via the over-flow. Best to use manual switch to fill well and then change to Automatic if you want to bring new water in and back out on a timed basis.

The Hydro-air pump is strictly a bubbler which adds air to the water in the wells. It should not be used when the aerator is running, since the aerator is bringing in new water. I use aerator to fill and then shut it off and run Hydro on timer in hot weather.

These systems use 2 different pumps. One (aerator) is down in the bilge and the Hydro is behind the livewell... Others here can help with precise locations, etc...