how do you calculate mashtun efficiency? also is there a benifit to recirculating during the mash and if so how fast would you recirculate with a pump?

You can find your effiency by taking your actual OG and comparing it to the theoretical OG that you get from promash,other brew software or by hand calculation. Keep in mind that your effiency can vary from brew to brew even though you are using the same setup for both.


Cheers,
HH

Recirculate slowly with a pump. Going to fast can compact the grain bed. I shoot for a speed that would be about the same as gravity flow.

And yes, there is a benefit to circulating during the mash in that you don't have to at the end of the mash. In other words, you should circulate before sparging until the wort if free of particulates (it may still be cloudy). If you currently circulate before sparging, then circulating during the mash won't buy you much. It does help even out the temps and I'll bet it helps efficiency some but not much.