I was at Bob White's sugar house on the Vermont Maplerama tour where he was demonstrating him sap agitating system. He was using a SS Goulds water pump to recirculate the water (sap) through 2" PVC pipe with a series of 1/8 holes drilled in it. If I recall it correctly, I think that Bob talked about recirculating the sap for 12 hours. What I do remember is that he said DO NOT USE A COMPRESSOR WITH ANY OIL IN IT.
Joe
2004- 470 taps on gravity and buckets
2006- 590 taps on gravity and buckets 300 gph RO
2009- 845 taps on vacuum no buckets, 600 gph RO
2010- 925 taps on vacuum new 2 stage vacuum pump
2014- 3045 taps on vacuum, new 1200 gph RO
2015- 3104 taps on vacuum
2017- 3213 taps on vacuum
3' x 10' oil fired evaporator with steamaway