[ddeck]

>The larger the surface of the filter the easier time the fan will have to push the air through it and more efficient it will be.

This is quite true. Assuming the media in your particle filter is of sufficient quality, the most important metric to look at is the aggregate surface area. The larger the surface area, the more air you will be able to move through it and the more particulate matter it will hold before requiring replacement.

Particle filters use pleated media for this reason. It's not uncommon to see a filter with 1 square foot face having 50 square feet or more of media. Without specs, the thickness of the filter and the density of the pleating will give you a decent estimate of the filter area. To improve performance and longevity further, it's also typical to have a coarser, pre-filter.

The machine itself is just a fan to push air through the filter and as noted, any reasonably powerful fan will do a sufficiently good job. High quality machines are only really required where you're filtering air before it enters a given area (e.g. LCD/semiconductor plants), and thus cannot afford to have any unfiltered air leak past the filter.

[lmilcin]

The quality of the filter is important if you want to remove very fine particles.

Even good filters do not typically remove all particles, only particles above certain size. If you have cheap filter it may not even capture a portion of the particles you are interested to remove, it may remove none no matter how many times you cycle the air.