yes they do lower surface tension and thier break down does increase BOD - but their main action is to increase phosphates which are the limiting in freshwater ecosystems. This increase in phophates allows for increase algae growth with then depletes O2 rather than O2 depletion been direct.
Soaps themselves have a high BOD - small amounts can have a significant effect on pools plus they a high pH. Most aquatic life will tollerate a greater diversion form pH 7 to the acid side (ie lower) than on the basic (high) side.
Both general detergents and soaps are not good new really - that said a few drops in a loch isn't going to do much harm but if multiplied or a very delicate ecosystem...
Non ionic surfacants that are Purpose manufactured for easy "eco-friendly" biolocial break down are better.
Soaps themselves have a high BOD - small amounts can have a significant effect on pools plus they a high pH. Most aquatic life will tollerate a greater diversion form pH 7 to the acid side (ie lower) than on the basic (high) side.
Both general detergents and soaps are not good new really - that said a few drops in a loch isn't going to do much harm but if multiplied or a very delicate ecosystem...
Non ionic surfacants that are Purpose manufactured for easy "eco-friendly" biolocial break down are better.