Thanks for your replies 
sounds to me like it is over filled and channeling inside the vessel, take a little bit out if it is new and allow the resin to move freely
How do I know if I've over filled it? I didn't fill it right to the brim...
Andy
did you compact the resin when you was filling it ?
What I mean did you fill it up with resin, then shake it then fill it up more ?
easy way to fill out if it is over filled is take some out, add riser back in fill with water and skake it to displace the resin beads, if the tds is not lower after a min or two then it is not this.
Let us know how you get on
