You'd have to flush the bulb with co2 before re attaching.
Yeah, that's where I was leaning. Maybe go ahead and get a bottle and regulator, just for that purpose. Just drop the hose in there open ended while I'm cleaning up the ball valve. It's heavier than air, so will purge out most of the air. There will still be that tiny bit between the top of the bulb and the face of the ball valve, but it'll be a tiny bit, for sure. The flange on the bulb barely clears the ball in the valve. Then, of course, the bubbles will just be (mostly) CO2.
I kinda thought about doing a closed loop rig if I do the CO2 thing. Put something on the bulb to vent it to the top of the fermenter so that liquid just forces the gas out, and use CO2 to purge, thus just putting CO2 on top of the beer in the fermenter as it drains into the bulb. Gonna be a little tough finding a bulkhead fitting small enough to avoid the radius problems on the bulb, though. It's only 1 quart (0.95L) for each time I harvest. I usually let it run for about a week before I harvest the first time, then a second harvest (which is what I keep for the yeast) I do at bottling. Last round of bottling showed me I need to flush the valve before I start dumping to the bottling bucket. Still had a bit of slurry in the valve that I didn't think about, and dumped that right into my priming sugar solution. DOH!
Still learning the best techniques with this thing. I do like the improved clarity from 'secondary' fermenting and getting rid of the goo before I bottle it. Now I want to make sure I'm doing everything I can with it to avoid spoiling a batch. Albeit, I don't see much difference in the exposure by swapping that bulb and using the autosiphon to rack it to the bottling bucket or secondary ferment. My first try on dry hopping was with buckets for fermenting, and I racked to secondary before dropping the hops to make sure the trub didn't mess with 'em. WIth this thing, I yank the bulb off, sanitize the hop basket, put the hops in the basket, put the float (also sanitized) in, put the hops in. Take the top off the fermenter, drop the hop basket, put the top back on, put the bulb back on, and open the valve to the bulb. When the bulb is full, I put the airlock back on and leave it till bottling day.
I've noticed batches seem to go dormant a LOT earlier with the conical than they did with the buckets. Maybe it's my imagination, but it almost seems I could be bottling well under 2 weeks, especially with extract brews.