Operating system for swimming pool

Claim 1

A VALVELESS SYSTEM FOR MAINTAINING A SWIMMING POOL, WHEREIN THE POOL IS PROVIDED WITH A NORMAL WATER LEVEL LOCATED NEAR ITS TOP, COMPRISING A FLOW CIRCUIT INCLUDING A FILTER AND A PUMP AND TERMINATING IN TWO FLOW LINES, ONE OF WHICH ENTERS THE POOL ADJACENT ITS FLOOR AND THE OTHER NEARER THE TOP OF THE POOL AND BELOW A HORIZONTAL PLANE REPRESENTING THE NORMAL LEVEL OF WATER IN THE POOL, THE LATTER FLOW LINE EXTENDING THROUGH THE FILTER TO THE INLET SIDE OF THE PUMP AND THE FORMER FLOW LINE CONNECTING TO THE DISCHARGE SIDE OF THE PUMP, AND AN UPWARDLY DIRECTED FLOW LINE FROM THE LOWER PORTION OF THE POOL AND EXTENDING TO FORM AN INTERSECTION AND TO COMMUNICATE WITH SAID LATTER FLOW LINE, BOTH THE FILTER AND PUMP BEING DISPOSED BELOW SAID HORIZONTAL LEVEL, A PLUG TO CLOSE THE END OF SAID LATTER LINE SO THAT THE PUMP CIRCULATES WATER FROM THE LOWER PORTION OF THE POOL THROUGH THE FILTER AND BACK TO SAID LOWER PORTION, AND A TUBULAR FITTING EXTENDING INTO SAID LINE END TO CLOSE THE MENTIONED INTERSECTION SO THAT THE PUMP CIRCULATES WATER FROM SAID TUBULAR FITTING THROUGH THE FILTER AND BACK INTO THE LOWER END OF THE POOL.