Just an update-

I did find a UK site selling some American aluminum pool filter cleaner- I guess that has the GHT female threads.


Fill Clean & Empty Cleaning for Hot Tubs | Spas | Pools

on the same page they sell a 3/4 bsp connector- I did email them a couple of hours ago and I was amazed to find that they have just replied (on a Sunday)- saying that it does indeed fit the American product.

I guess I will have to see if nylon Vs nylon threads works as well as their nylon vs aluminum.