Using 23L plastic carboys for primary fermentation (30 bottle kits)

[Berry454]

So I have a fair few of these 23 litre plastic carboys and I was looking to primary ferment 30 bottle kits in them.

I was thinking, we often brew 6 bottle (4.5l) kits in 4.5l glass demi John's simply by filling to like 4 litres, letting ferment for 3-4 days then topping up to 4.5 litres for the last few days of fermentation when it settles down foaming.

Any reason why we can't do the same in 23 litre carboys with 23 litre wine kits?

Say I filled the 23 litre carboy to 18 litres. Let it ferment for 3-4 days (until vigorous foaming fermentation settles down) then topped up to 23 litres for the last few days for the rest of the sugar to ferment out slowly.

Would this work fine? Or can 23 litre carboys simply not be used for primary fermenting 23 litre wine kits? I know for the first few days the carboys would have very high starting gravities due to the kits being brewed short for a few days but this should level out providing they're topped up to 24 litres after a few days.

 

[Berry454]

Well I guess this isn't something that you guys regularly do so I've decided to just put it to the test.

I've brewed a Mangrove Jack's Pink Grapefruit IPA up to 18.4 litres in a 23 litre plastic carboy.

I'll give it a few days for the vigorous fermentation to end then I'll top up to 23 litres for the last few days of fermentation. (When I know it's not going to foam over).

Hopefully this works well and if so I'll start doing this with the wine kits. Just figured it was better to test on a cheap beer kit rather than a £70+ wine kit.

 

[RoomWithABrew]

There are key kegs that take 30 litres but you need to get the bags out.
I've fermented 25 litres of Brett beer in them. No crazy krausen on Brett, much like a wine fermentation.
I use the smaller key kegs for secondary.
Fermentasaurus is real game changer for wine, no transfers, less wine loss and quicker.