Hi bobsbeer, yes I'm looking at using speed controllers. http://m.rs-online.com/h5/mobile/uk/cat ... 7480832%2F
But I'm gong to trial one at the weekend because I know the pumps speed to flow ratio isn't linear.
Even if that is a success I'll still need a valve on the RIMS to keep it full, I'll ammend the PFD. Thanks for that.
I do underlet, it worked a treat on my old system using gravity but on this I will have to pump. I can throttle the flow on the MT valve. If I add another inlet on this 2 pump system it will make the pipe work more complex so I'll stick with underletting from the outlet unless I change to 3 pumps.
That's a great idea recirculating the HLT, it's a problem I did foresee but thought about just giving it a stir with the wooden mash paddle.
Have you any pics or drawings of yours?
Thanks for the input.