How to Replace a Sand Filter Pressure Gauge. If you have a pool, you should know how to perform basic maintenance and repairs. If you think the pressure gauge has stopped working properly on your sand filter, it might be time for a replacement. Corrosion or mineral buildup in the gauge can cause issues with pressure readings.
Turn off the pump motor on the filter, and let it drain by opening the airbleeder and changing the valve to drain. Shut the airbleeder, and turn the valve to the closed position. Locate the dial valve. The pressure gauge is on the side of it.
Unscrew the pressure gauge by turning the assembly attached to the dial valve to the left. You might need a crescent wrench. Take the gauge with you when you buy the replacement from the pool and spa store to make sure that the new one has the same diameter screw and the same amount of space between threads.
Clean the inside of the hole for the pressure gauge with a solution of baking soda and water and a toothbrush. Get any mineral buildup out of the hole.
Wrap plumber's tape around the threads on the new pressure gauge, stretched tightly, four times. Screw it back into the hole until it's tight and secure. You might need to use a wrench on the last turn to get it straight up and down again. Return the valve to the filter position and turn the pump motor back on.