A Surfacant! :angel: Showing off a bit. I first heard about these when my son was born premature, there is a substance in the lungs that stops the two sides sticking togther. What the stuff does in a water context is to breack the liqiuds surface tension. It is also used by Fire Services in AFF mixes. Ordinary washing up liquid is a surfacacnt. , but then so is standard Anti Freeze. So waht your doing is making the water more slippery.