It has to do with the second stage, water is getting inside from somewhere, mouthpiece, inhalation diaphram, exhalation diaphram or even a cracked body. You can try and seal off air inlet from 1st stage, then try to draw air off reg and should get none, if you do try to find where. But, honestly any regtek worth his weight in salt should be able diagnose/repair this easily. I have seen it all, sand, flim, chunks, spiders, roach stuff and silcone eating roaches. Just get it fixed somehow, it can be dangerous to breathe in spray.