Carboy Cap- 3, 5 & 6 Gallon Carboys

Well made, seems like it will be easier and more secure than a normal stopper. Doesn't fit on my 3 gallon glass carboy. I'm planning on doing 5 gallon batches later, I'm sure it will fit a 6 gallon primary.Update:Doesn't fit on my new 6 gallon carboy either. The cap is way too big, or my carboy neck is too small. I'll stick with regular stoppers.

I wanted a cap that would fit a bubbler and block out light when used with a carboy cover. The problem is that it's not air tight. I figured that out immediately and didn't want to change ruining 5 gallons. Then I figured out I could cut a hole in the middle for the plug and still use it to block light. So it helps, but it's not the intended purpose.

This does NOT replace a regular carboy stopper though. It is helpful for me in other things such as vacuum degassing and transferring to secondary carboys or bottling buckets. Someone else pointed out how it can be used to start a siphon without a special siphon device hand pump too. The seal is not that snug so you might need some vaseline to help with that.

This product looks a lot nicer than the normal rubber bung stoppers, but it will not hold an airtight seal. At first, I thought my beer was not fermenting but after closer look, this cap was just letting all the gas out of the carboy from the edges. When I changed out the stopper for my usual rubber one, the airlock was bubbling again.This product is good for minimizing the oxygen during transfer and racking, but don't buy this for use with an airlock unless you want rotten beer, cider, etc. a few weeks after brewing.Good price, but made my beer go bad from O2 exposure. Will be looking elsewhere for a nicer stopper.

Run-of-the mill carboy cap. Excellent for racking. I've had some that fit a little more snuggly on the carboy mouth than this one and could be used to hold an airlock during active ferments rather than a stopper. I wouldn't try that with this one as it's a little loose fitting. For racking, though, it's just fine.

It does not seal well to my glass carboys. Racking cane down the center and C02 hose connected to the side should start a good flow...but no. I have to squeeze the cap to the bottle during transfer or the C02 leaks by and no flow. I bought 2 and both are crap.

Does not fit the carboy properly allows the co2 to bypass the air lock. It's too lose on the neck of the bottle. worthless for making wine

These caps don't seal very well on 5 gallon carboys. My airlock often doesn't bubble because of leaks. I recommend this for primary not secondary fermentation.