I have been battling a cloudy pool, so this morning I opened my filter to see if it was "channelled". Being very honest, I do not know what "channelled" looks like, but was hoping that I would aleast be able to see if there was clumping. So, as suggested by another poster, I first looked in - didn't see anything too abnormal - some lighter colored fine substance on top of the sand, but not an enormous amount. So then I took the water hose- with water running - and began to allow the tank to fill and run over. Then I gently worked the tip of hose into the sand. That is when really yukky water began to come out of the center tube in the tank. I would leave the hose in place until the water from the center pipe would clear, then move the hose to another spot. Each time leaving it in place until it cleared. In most places, the hose easily slipped into the sand bed, but in some places it met resistance. I worked around inside the tank until the water ran fairly clear, no more "yukky" spots found and the sand was easy to slip into all around. Was my filter channelled?