More progress!
Well yesterday I went and collected my new sump

Yay, another piece of the puzzle has arrived. I have just put it in place, however the work on the sump room is barely started so please ignore the complete mess!
This morning i made a stand to put the roller mats on so they will be at the right height to feed into the sump and I feel it will work very well.
Here is my water change station that i built last year. It is filled by a 600GPD RO unit. The top tank is fresh water and the bottom is the salt mixing tank, Each tank hold around 200L. It sits right next to the sump so water changes will be as simple as pumping out old water and then opening a tap to refill. However i may look at automated daily water changes.
Also i have made myself a manifold for the closed loop system, It consists of 6 x 50mm reducing tees down to the 25mm i need. The plumbing behind the tank will have to be very creative as there are a lot of pipes and not a lot of room!
Thanks for looking.