What problem occurs when backwashing an airbound filter?

When backwashing an airbound filter, the primary issue that arises is that the media within the filter can become suspended in the wash water and subsequently flow out of the filter. This situation typically occurs when air pockets are present within the filter media. When the backwash cycle is initiated to clean the filter, the agitation and the force of the water can dislodge the filter media, which may not be adequately saturated or compacted due to the presence of trapped air. As a result, some of the media is flushed out with the wash water, leading to a reduction in the filter's overall media volume and potentially impairing its filtration capabilities.

Understanding this phenomenon is crucial for effective filter maintenance, as losing media not only risks filter integrity but can also affect water quality. The other options reflect issues that are generally associated with filter performance or operation but do not directly correlate to the specific problems caused by backwashing an airbound filter in the manner described.