About to ferment a 10 gallon batch in a cut off keg. The entire top is cut off and is just like a pot. Gonna cover with some layers of plastic wrap and hold that on with a rubberband. I figure the CO2 will still escape. Any ideas about how to incorporate a blowoff hose in order to watch the bubbles.
IMO this will work fine for a short term fermentation. I would use a plastic bag (or two) cut to size to fit nicely over the top of the keg. Then take a long piece of string and wrap it several times around for a secure fit.
Most likely you willl not need a blow off for ten gallons in a 15 gallon keg. Rack to kegs once the plastic is no longer billowed up and exhibiting postitive pressure. I do something similiar in a 11 gal stainless pot w\out problems.
Keep fermentation temps in check w/ a large batch like this as the heat of fermentation may raise the batch temp.