Carl Beyer wrote:
Wanted to hear thoughts / results. Considering it for my 400 gallon
pond. I have heard great things...

I've got one in my pond (somewhere between 15000 and 20000 litres and
far too many fish). Ammonia levels aren't zero but are right at the
bottom of the scale on the test kit.

I wouldn't buy one though, they're easier enough to make with a pipe and
some coral sand.

--
Matt Helliwell
Matt at Matt The Rat dot com