Firstly, Jim, thank you, I needed to be told.
Well I've just had another read up on the GL site (something I didn't do before converting my wash tank) and I've made a couple of mistakes,
1, I used 15mm pipe.
2, it's position was guesstimated.
So with all the info available to me I just forged ahead from memory.
Keith, I should have taken you up on the offer of the valve as well as the misting head.
So the concensors is an emulsion was the reason it overflowed, I can see why and tend to agree with this.
On the plus side my new defuser has worked nicely,
on the down side I lost 15 to 20L due the overflowing problem.