"Oz" wrote in message
...
Brian White writes
Sorry Gordon. I guess I am too defensive! In the past, I have had guys
saying that it is no better than the mist off the half meter waterfall
and it stings! The thing works and nobody has yet put it to scientific
test.

Eh?

You are talking about a hammer pump?
They are common, well known, and well scientifically described.
There are even web pages on it and a long discussion here about them
some years ago.

It's an air lift pump.

Gordon