Quick video of what happens over time with the stainless steel filter “bubbling” and no longer taking water. This video is representative of thousands of similar examples that can be provided upon request and is the direct result of the difference in the way the uPVC base expands in hot weather vs the surgical stainless steel filter. As the base swells it stretches the filter, after it cools and contracts — bubbles!
Since the system only works because the base breaks the surface tension above, you get overshoot in even the slightest rain.
This major issue wasn’t obvious until several thousand systems had been installed over several years. This has been corrected in the redesigned model available at www.mastershield.com.