I don't really want to wade in here, but settle down guys, although I'm the last one to complain about people arguing.
Johnny, Smicko was referred to having a zone of plants that breaks down the garbage in the water. That is what he meant by the term 'growth'. Growth of impurities in the water. Given that the climate is warmer here, you would expect this to more of an effect than in the UK.
You thought he was referred to an increase in water due to temperature. A simple misunderstanding.
So, get back to the crazy idea of a digging cess pool in your own backyard

and everyone stop getting personal.
Would anyone want to dive into a friends 'natural' pool like that? No way, give me a clear chlorinated swimming pool any day! Sometimes 'natural' is not a fun thing.