Begin the backwash at a slow rate and gradually bring it up to full flow. Air binding can aggravate media loss during backwashing but may not be the only cause. To further minimize media loss, turn off the surface wash one or two minutes before completing the backwash cycle. Also keep in mind that the filter bed is completely fluidized at 20 percent expansion, and it may not be necessary to expand the filter any further to adequately clean the bed. If after following these recommendations you are still losing more than a half inch of media a year, the solution may be to raise the level of the washwater troughs.
Air binding is just one of the problems that can sabotage optimum plant performance.
Many of these problems are seasonal and one of the best things you can do to minimize their impact on operations is to keep good records. By tracking what works best for you under specific circumstances and over time, you can predict many of the water quality changes that will affect operational processes long before they are a problem. AWWA filter resources Filter operation is an often misunderstood part of water treatment. So much of what is going on in the filter is hidden from visual inspection so we must often depend on indirect feedback for operational cues. Hands on instruction is the best way to learn filter operation, but unfortunately this kind of training is scarce.