A safety inlet drain assembly for main and skimmer drains of a swimming pool includes a perforated cylinder in the drain cavity mounted at a lower end on the drain return line and having a domed cap on the upper end to which the drain gate cover is attached by fasteners. The disk is spun at a first speed RPM\u20141 using a first value PGT\u20141 selected for the PGT, and the disk is spun at a second speed RPM\u20142 using a second value PGT\u20142 selected for the PGT, wherein the second value PGT\u20142 is generated in response to the first value PGT\u20141 scaled by a function of a ratio of RPM\u20142 to RPM\u20141. The holding elements comprise a ring for blocking in rotation the cartridge adapted to be connected to the cartridge by positive locking members provided on one end of the latter and positive locking members provided on the ring. The sampling becomes sparse and the reward function is discounted as one propagates further in time.