Which condition indicates a problem with filter performance?

Unstable water levels before and after the filter indicate a problem with filter performance because stable water levels are essential for consistent filtration. When water levels fluctuate significantly, it can suggest issues such as filter clogging, ineffective filtering media, or operational problems with the filtration system. This instability can result in inconsistent flow rates and compromised water quality, suggesting that the filter is not performing as intended.

In contrast, consistent improvement in filter head loss typically indicates effective filter performance, as it suggests that the filter is adapting well to changes in water quality. Increased backwash effectiveness usually means that the filter is being properly cleaned, which is a sign of good performance. High clarity in treated water reflects successful filtration; thus, it is not indicative of a problem. All these aspects underscore why unstable water levels serve as a direct sign that the filtration process is not functioning correctly.