>It might fall short of the official specs, but its difficult to argue with their results. For this one would need to know the exact measurement setup. For rea

>It might fall short of the official specs, but its difficult to argue with their results. For this one would need to know the exact measurement setup. For real world performance it is important to know the approximate exchange rate of air of the room. The throughput of the fan across the filter must be considerably higher than that. >What kind of prefilter would one need? I'm thinking of DIYing this... First of all, you would need a radial fan to overcome the required pressure drop. As for the prefilter, I am from Europe, which has probably different standards than the US, but some overview is provided here: http://www.filtration-engineering.co.uk/air_filter_testing.htm http://www.filtration-engineering.co.uk/air_filter_testing.h... . For my clean room set up I had a EU5 prefilter combined with a EU9 main filter. Afair, laminar flow boxes for dirty environment (i.e. not supposed to be used within a clean room) have EU5 (or the equivalent) prefilters as well.