Hi! As the thread name states, I am wondering what the best form of filtering my 500L duck pond. It cheaper the better. I only have 2 ducks and I'm using a kiddie pool that I picked up for €15. It looks great when I clean it out and refil it with fresh clear water but that turns to this this green 'sludge' in a matter of hours! Id prefer a way to re-use the water rather than dumping and refilling as I live in a suburban home and I'd end up water-logging my garden every time that I empty the pool. Thanks a lot, Gary. Also, please excuse any spelling/grammatical errors, I'm using my phone.