Hi Ian,
Your DIY looks really professional.
Do keep your powerpoint diagram coming so that we can just print it out and take it to the manufacturer
I've got a few questions if u don't mind :-
1) Noticed the pipe from overflow to sump in your new design is different from your existing one.
New one look like letter "h", would u mind to explain its purpose ?
2) Also u r using double C-siphon and double return to sump.
That's to increase the turnover ?
3) The part of the OFB inside the tank and the part outside, are they 2 separate boxes ?
4) How do you attached the OFB to the tank, do u need holes in the tank ?
5) The part of the OFB inside the tank, is it adjustable acording to water level ?
Sorry for so many questions as I've never done one before but I'm very interested.
Thanks in advance.