I used the PondoVac 4 for the first time in a second-year pond that was not netted over fall & winter. Dense leaves and silt at the bottom. The vac attachments often clogged, but this was due to the density of the leaves - for which I blame myself. After about 30 minutes of vacuuming, about 20-25 lbs of wet leaves and silt were removed - two discharge bags full. The pond water is noticeably clearer the following day, and cleaning the vacuum and filters afterwards was a breeze. Essentially no delay in discharge allowing for continuous suction. Be wary of attachment clogs in dense muck, and this item will pay for itself in effectiveness.