Rule of Thumb for Changing Filters
The rule we have followed for 18 years in the filtration industry is to change filters every 6 to 12 months. Six months is almost always optimum, especially in commercial/office settings, and twelve months is as long as you want to go no matter what. Changing the filters at one year maximum is based on the following two reasons: filtration media does get saturated/used up, but more importantly, even if the media isn’t used up due to low usage, at a year we want to remove the wet, warm, dark media (filters) to prevent possible bacteria buildup inside the filter casings. The main concern, at one year, is the keeping of sanitary conditions (preventing bacteria growth) through regular filter changes. Secondarily, there is a concern over media saturation when going past a year. Carbon will pull down chlorine (a Volatile Organic Chemical or VOC) a lot longer than it will pull other VOCs like ammonia, Trihalomethanes, and Chloramines. We have followed the stated rule of thumb, changing filters every 6 to 12 months, for the 18 years we have been in the business and it has served us well.