Thanks Dave.
I had the carbon block in the cannister upside down!
Changed it round an checked all the connections, went through fine and got it down to 9ppm after a flush, I take it that is a good amount before it goes through the DI?
Just one more question, what is the cost and how easy is it to attach an auxillary pump to the 300 to increase the pressure and reduce the fill up time?
I have worked out to fill a 650ltr would take 27 hours.