The supply water stays on at all times when the pool sentry is in the pool. As the float drops, the water turns on. When the float reaches its set height, the water shuts off. The float adjusts to the desired level, usually a point halfway on the tile line or skimmer.because the hose is under constant water pressure, it is essential that the customer uses a heavy-duty, reinforced hose. A flyer in each box offers customers an aftermarket hose. It is rated to 200 psi working pressure and 750 psi burst strength.