An Airflow Question About Merv Ratings (Air-handler Filters)

Is there a difference in the airflow between a Merv 7 -vs- Merv 11?
These are the filters http://www.airguard.com/pleated.html I'm talking about in case brand makes any difference. I'm looking at the "DP Max" (merv 7) vs "Powerguard" (merv11)
I see they have an efficiency rating, whatever that is. Does a Merv 11 restrict more air than a Merv 7?
I'm looking for good airflow and a "HEPA type" filter combined.
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use_a snipped-for-privacy@yahoo.com wrote:

A higher static pressure will restrict more of the airflow.

You need to know the air velocity through the filter then look at the initial resistance or pressure drop. Hopefully you return air & filter grille were sized so you have 300-FPM rather than 500-fpm or more! One for example has .26 pres. drop at 300-fpm but .54 pres. resistance at 50-fpm air velocity through the filter! Most residential blower systems are rated at .50-ESP External Static Pressure. When the filter begins loading at 500-fpm you will have a big drop off in airflow! - udarrell
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Ask them yourself: http://www.merv.com/index.cfm
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