Sand filters are one type of filter commonly used for swimming pools. Sand filters work by passing pool water through a tank holding sand. The sand cleans the water by catching and filtering out impurities and debris from the water. Sand filters are exposed to high water-pressure and the weight of sand constantly, which can cause problems to occur within the filter. One common problem is a small leak located on the top of the sand filter.
Examine the thin metal band, called a band clamp, around the top of the filter. Use a screwdriver to tighten the band clamp and ensure a leak cannot continue in that area.
Examine the sight glass of the filter. The sight glass is a small clear glass container that is screwed onto the side at the top of the filter. For leaks coming from the sight glass, unscrew the sight glass and apply Teflon tape to the grooves of the glass, then screw the sight glass back into place.
Turn off the filter system. Check the dial valve on top of the filter and ensure it is seated firmly in place. Poor positioning of the valve results in pinching of the o-ring underneath, which allows water to escape the filter. Try moving the dial valve to a few different settings, and then back to default.
Check the backwash line of the filter for leaks. Ensure the small clamp over the backwash line is tight. When not using a backwash hose, insert a plug into the backwash line to prevent leaks.