Hayward SP1056 - Hydrostatic Relief ValveProtect your pool structure from hydrostatic pressure buildup with the Hayward SP1056 Hydrostatic Relief Valve. Designed to automatically relieve excess groundwater pressure beneath the pool, this valve helps prevent pool shell damage caused by ground water rising during heavy rain or draining. Manufactured to Haywards OEM specifications, the SP1056 features durable, corrosion resistant construction for dependable performance in demanding underground