I recently lost a bout a litre of beer through a leaking disconnect on liquid post.I do the same when I am not carbonating - both times it happened after I added fresh kegs and hooked them up to carbonate. I would have thought I'd be able to hear it a well, and I could have sworn I checked the duotight connections - but in the morning on both occasions a gentle pull actually removed the hose from one of he two new disconnects. (I am pushing them all the way in to the second click).
Don't know if I am doing something wrong with the duotights, or maybe worth replacing some of the connectors but I hadn't expected it to be so easy for gas to leak with this kind of setup as seems very widely used. Def could be a me issue.
Actually was not a problem with the disconnect. I thought it was probably a bad o-ring but when I went to replace it I found the problem was the machining of the post; I removed a sliver of steel (like a very thin, broken ring) which had not been cleaned off after manufacture.