At this point I've completed about 6 AG batches using fly-sparging with out too much drama. At this point my most memorable "learning experiences" have been about the effects of flow rate and stirring thicker mashes on efficiency. But as always I'm trying to improve my process and this part has me stumped.
In batch #6 and #4 I've had what I'd call a semi-stuck sparge. I'm using a 10gal. round rubbermaid cooler and a 12" SS false bottom (Northern Brewer's design) attached to the bulk head by 3/8" high-temp silicone tubing. I vorlauf about 5-6 quarts to clear things up and dial in a flow rate of ~1qt/min. The two times I've gotten this stuck sparge, the flow rate stays that way until I reach about ~2 gal of wort in the BK. At that point the flow rate begins to slow and I've noticed small bubbles climbing their way up the tubing from the BK to the ball valve on the MLT. Eventually the flow slows to a trickle. I opened up the valve to ~1/2, and flow started up again, but with a lot of grain material in suspension and at a higher rate than I wanted to sparge at. So both times I closed the valve, stirred the mash, let it settle and started to sparge again at ~1qt/min with no subsequent problems.
Has anyone experienced something similar?
A couple of things I've noticed is that in order to get flow going from the MLT in the first place, I have to open the valve pretty far in order to get the air out of the line. Once that happens I scale it back immediately to get my desired flow rate. Could this initial "burst" be contributing to a stuck grain bed later on?
I don't think it's a vacuum lock forming because stirring the mash has fixed the problem, but I can't be sure.
As I said, this has only happened twice but it seems to be a recurring problem. Any advice is welcome!
In batch #6 and #4 I've had what I'd call a semi-stuck sparge. I'm using a 10gal. round rubbermaid cooler and a 12" SS false bottom (Northern Brewer's design) attached to the bulk head by 3/8" high-temp silicone tubing. I vorlauf about 5-6 quarts to clear things up and dial in a flow rate of ~1qt/min. The two times I've gotten this stuck sparge, the flow rate stays that way until I reach about ~2 gal of wort in the BK. At that point the flow rate begins to slow and I've noticed small bubbles climbing their way up the tubing from the BK to the ball valve on the MLT. Eventually the flow slows to a trickle. I opened up the valve to ~1/2, and flow started up again, but with a lot of grain material in suspension and at a higher rate than I wanted to sparge at. So both times I closed the valve, stirred the mash, let it settle and started to sparge again at ~1qt/min with no subsequent problems.
Has anyone experienced something similar?
A couple of things I've noticed is that in order to get flow going from the MLT in the first place, I have to open the valve pretty far in order to get the air out of the line. Once that happens I scale it back immediately to get my desired flow rate. Could this initial "burst" be contributing to a stuck grain bed later on?
I don't think it's a vacuum lock forming because stirring the mash has fixed the problem, but I can't be sure.
As I said, this has only happened twice but it seems to be a recurring problem. Any advice is welcome!
