The cost of very high MERV filters can get pretty expensive. And while they may last longer, they still will need to be changed regularly. So, you will find yourself weighing the cost benefit, especially on the highest MERV ratings available.
We find it helpful to use the chart above and as such recommend MERV 13. It helps homeowners and businesses to filter more possible harming contaminants without going overboard on the cost.
The actual size of your filter may be determined by how the intake housing was constructed and installed. So, if you want a MERV 13 filter but a little bigger, more surface area, i.e. 4” thick, your system may need a slight modification. It depends on how it was installed. A little tape measure work where the filter goes should clue you in. If you need a slight modification, we believe it is worth it in the long run resulting in better filtration and better health, and a cleaner air handling system.