A friend of mine didn't have an alternative pump to empty his lay-z-spa and asked me if I could make him an adapter so he could use the lay-z-spa pump unit to pump the water through a hose pipe and into a near by drain.
the adapter screws directly into the water outlet inside the spa (you will need to unscrew and remove the diffuser first).
printed at 0.2mm resolution with supports, do not support the screw thread, just the 90deg overhangs. If my memory serves my right I printed this at 20-30% infill and it was a little bit leaky but still functioned as required but 100% infill may give you a part thats a little more water tight. you will need an O-ring for the top of the hose adapter.
Use with the shortest length of hose you can as a long hose could cause too much back pressure on the pump.