THE DISCLOSURE SHOWS A SPRING LOADED WEIR IN A SKIM TANK SYSTEM USED IN A SWIMMING POOL, THROUGH WHICH WATER IS CIRCULATED TO A FILTER. THE WEIR COMPRISES A SHEET OF SPRING MATERIAL SUCH AS LEAF SPRING FIXED AT ITS LOWER EDGE AT THE BOTTOM OF THE THROAT LEADING INTO THE SKIM TANK FROM THE POOL, AND IS PROVIDED AT ITS UPPER FREE EDGE WITH A LIP MEMBER WHICH IS OF A DENSITY AND DIMENSION TO CAUSE IT TO FLOAT AT THE SURFACE OF THE WATER WHEN THERE IS NO WATER FLOWING THROUGH THE TANK. WHEN WATER FLOWS FROM THE POOL TO THE TANK, AS WHEN A CIRCULATING PUMP IS TURNED ON, THE WEIR IS BENT DOWN SO THAT WATER CAN FLOW OVER THE LIP INTO THE TANK.