Measuring your filter bed expansion is necessary to confirm that you have a proper media backwash. Filter bed expansion changes based on water temperature, backwash pump performance, and other system parameters. It should be verified at least seasonally as water temperature changes and more frequently as may be necessary.

If the filter bed expansion is out of the desired range it can be the beginning of problems for the filter. For example, if the expansion is too low this means the media bed is not being cleaned as well as it should. Several conditions are attributable to this including mud ball formation, calcium carbonate buildup on media particles, underdrain clogging or improper media stratification, among others.

If the filter bed expansion is far above the target value it could lead to loss of media over the backwash trough as well as excessive use of backwash water.

Tetra Tech’s Filter Bed Expansion Measurement Tool is a quick and easy way to check bed expansion. The Tetra Tech tool uses a highly visible reference disk, or measuring plate. The measuring plate is attached to a telescoping pole that can be extended as far as 16 feet with the standard version and up to 20 feet with the extended reach version.

Minimize wasted backwash water, protect expensive media, maximize filter efficiency, and reduce operations costs with the Filter Bed Expansion Measurement Tool!