a short distance below its capped upper end the pipe 24 is provided with two water delivery ports 28 located directly opposite each other on opposite sides of the pipe 24 the pipe 24 is concentrically centered within the cylindrical cavity formed by tube 26 and it passes through the flat horizontal base of the cavity in making connection to conduit 17 the top surface 29 of tube 26 is flush with the surface 30 of the plaster coating 31 of the pool structure 10 tube 26 may be of any suitable plastic or metal material commonly employed in plumbing systems the pop up head 25 has an outer cylindrical surface that fits loosely inside the tube 26 head 25 incorporates an upper cylindrical cavity 32 and a lower cylindrical cavity 33 the two cavities being separated from each other by a diaphragm or horizontal wall means 34 which may be formed of a resilient material such as plastic or rubber both of the cavities 32 and 33 concentrically surround the delivery pipe 24 and depending upon the instant vertical position of the head 25 one or the other of the two cavities may receive water from the interior of pipe 24 via the ports 28 as shown in fig2 two rotator jet drive ports 35 and 36 extend from the upper end of cavity 32 to their respective points of exit 37 and 38 at opposite sides of the periphery of the upper end of head 25 the main water delivery port 39 as shown most clearly in fig3.