Retrying my bentpoke crankshaft that failed last batch due to o2.
This batch i tried this and also have put the hops into the keg and purged to give it a really good shot.
Has the usual bad hop taste at present that should mellow out soon.
Will let you know how it turns out.
Personally I think this is a pretty impractical solution, couple of points -
The CO2 coming off a ferment isn't pure, especially the first 1/3 - 1/2 of the ferment, it contains a bunch of volatiles we don't want to put back in the beer, it will also contain O2 from both the beer and the head space, especially the first 1/3 of the ferment.
If you pay $10/kg for CO2, the molecular weight of CO2 is 44g/M 1kg of CO2 is 22.7Moles, each Mole has a volume of 22.4L so 1kg of CO2 is 509L.
If that balloon holds 5L I would be surprised, but hey what the hell. 509/5 = call it 100 balloons.
$10/100 = is 10cents.
Just how much stuffing around and increased risk of infection and reintroducing unwanted oxygen and volatiles do you really want to do for 10 cents?
Inflate the Balloon with pure CO2 if you really feel that its an issue, me I just put a cotton ball in the end of the airlock as the beer cools it traps any bugs (look up Tortuous Path Entrapment). If you play around with the change in volume of the headspace as the beer cools I suspect the amount of O2 ingress will be 2/3 of FA.
If its a serious issue I would opt for a cask breather and keep the head space full of pure CO2 from a normal supply.
Personal opinion, I have a snub nose and I really like it. If you have the space for the snub nose over the all rounder I personally believe it's a better design and it's also made in Australia as opposed to China where Kegland source their fermenters.
I am not affiliated with either KK or KL and I buy from both.