Dusty asked about UV lights and airflow in HEPA filters.

I have never used the UV light in a laminar workstation. In fact,
there is no strongly compelling reason to use them in the first place; the
only occasion where one might use it is if massive contamination was
suspected (even then, one should find the source, rather than treat the
whole darned thing) in the filter element or elsewhere in the hood, or if
the filter has been moved or in storage for a long period of time. Even
then, leaving the fan on for 24 hours should blow out virtually all the
gunk on the downstream side of the element. A quick wipedown with 70%
ethanol is good enough for the working surfaces.

Using these principles at work, I suffer the least contamination
of anyone who works in the plant tissue culture group. I can't remember
the last time I had contamination in a tissue culture, in fact.

As for airflow- total CFMs won't do anything for you. What is
more important is the face velocity, which should be 90+ linear feet per
minute. You can get this from CFMs by determining the size of your
working face, and dividing CFMs by that number. Of course, it's much more
practical to measure the working face velocity, since you never know how
many CFMs your fan is putting out- unless you trust the label. And if you
trust the label, then why are you having to determine how much air you're
moving?

In reality, much lower velocities are fine, provided your
technique is good, and nobody walks behind you while you're working at the
filter.

The e-mail address in the header doesn't work. Sorry.

-AJHicks
The Orchid Seedbank
Chandler, AZ