Is it more effective than pouring hot water down the drain? I thought the foaming and agitation was quite gentle.

Here’s the REAL trick: Jam the plug in immediately after the vinegar and hold it down. So all that foaming is directed downwards, including the pressure. It’s not enough pressure to blow out a pipe, but it is enough to clear stank out (more importantly, it agitates what’s in the trap and a sluice afterwards will also voom out anything caught in the curve)

fruit fly larvae are pretty sensitive to salinity and ph changes, so it doesn’t matter how wild and free you go with the mix, btw.