When choosing a discount filter in this size, you have three options. There is the basic fiberglass filter, the permanent reusable discount filter or the more efficient pleated filters. All of the different filters have a varying efficiency in filtration and separate replacement schedules.

The fiberglass and reusable discount filters have a Minimum Reporting Efficiency Value (MERV) rating of 4 and 5, respectively. This range will allow the filter to catch particles as small as 10 micrometers with a 95% efficiency. Most of the particles in that size range will be pollen, dust, insect debris and textile fibers. The main difference between the two is the filter's life span. The fiberglass filter will have to be replaced every month to maintain high quality breathing air, but the reusable filter can last a lifetime. All of the debris that builds on the filter can be washed off, and the filter can still be used.

All of the pleated filters will have to be replaced every three months, but they all perform more efficient filtration than the fiberglass and reusable filter. The pleated filters have MERV ratings that range from 8 to 13. The MERV 8 filter will catch particles as small as 3 microns, which includes mold. All of the pleated discount filters give great protection for people with allergies and work great on large scale buildings.