Things might have changed over the years and have not looked into one of these since throwing out the last one that was given to me by the Mfr. to evaluate. This was the 2nd type of reusable one I evaluated, and it had washable plastic media that was of the electrostatic stye (1st one I evaluated was a cleanable metal media that you spray with fish oil for arrestance after cleaning). Used it for a few months and cleaned it once or twice as I recall. Observed it causing my furnace to short cycle and promptly tossed it. This is when your furnace trips on high limit and shuts off the burners to cool itself down before restarting the burners - while trying to satisfy the thermostat setting. You "do not" want this to be happening.
Electrostatic filters (at least the one I had) start with a new clean media that builds up static pressure over time due to the dirt/dust it traps. This causes the fan to be slowed down due to observed higher external static pressure (ESP). After cleaning it the first time - it will be starting at a higher static pressure drop than when new. The higher the static pressure, the more energy is consumed by the fan trying to overcome that ESP. It also causes a leaving air temperature rise (or fall in cooling).
You want to maintain your originally set fan air speed as close as possible to avoid this scenario - possibly causing your furnace/air handler to short cycle/overheat (high limit trips), premature fan motor and/or controls failure, or A/C (compressor) failure due to low fan speed. All systems have safeties built it to protect themselves from these scenarios, but you'd be wise not to bring about HVAC repair bills for premature system failures.
Throw away filters are the cheapest and best approach to to avoid trouble. I buy mine at Home Depot and they run about $7-8 for a three package. Don't buy the flimsy cheap ones you can see through - they catch very little dust. Change them at least 3-4 times/yr.
And don't get me started on electronic air cleaners, or HEPA style. Electronic air clnrs and HEPAs are expensive to purchase, as well as maintain. Electronic air clnrs weaken over time, and their ability to work properly is hampered (they also are known to cause ozone odor called smelly sock syndrome). HEPAs (large pleated filters, where replacements are bought through your HVAC installer) will experience high ESP if not maintained - just like the cheaper T/A ones you need to replace on a regular basis (only HEPA replacements are not cheap...).
