Seal A Leak is a highly effective, concentrated formula designed to seal plumbing and shell leaks in virtually any spa. It seals holes up to 1/8" in diameter and forms a permanent bond. Simply remove your filter, add solution to the spa water during filtration cycle and allow the repair to mend. Seal A Leak"s formula equals or surpasses other leak sealers on the market. Compare to Marlig Fix-a-Leak or any other brand. Seal A Leak is by far your best buy. Keep a spare bottle on hand. NOTE: No leak sealer will repair worn-out, leaky pump seals, which must be replaced.