Hello all,

We're still working on our river exhibit and have run into a problem with
our stream table exhibits.  Currently, the prototypes we developed use fine
plastic granules as the "land" that the stream passes through.   The water
flows from a faucet, passes through the gravel on the table, through a
filter in a drain and is pumped back to the faucet. Unfortunately all of
the filters we've used so far end up getting quickly clogged with gravel,
which in turn dramatically slows the flow of water from the faucet, making
the exhibit less effective (and more of a maintenance problem, too).

Do any of you have suggestions either for filters or for other media to use
as the land?  I should also say that part of the problem is that children
like to pile the gravel up on the filter to *try* to clog it up.  Surprise,
surprise!

Thanks for your help,
Bill

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William H. Stirrat  (Bill)
Evaluator/Market Researcher
Our Minnesota Science Hall
Science Museum of Minnesota
30 East 10th Street
St. Paul, MN  55101
phone:  612/221-9442
fax:  612/221-4514
[log in to unmask]

As always, opinions expressed are my own.
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Bye!