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Hi all--

I haven't seen any mention of UV filters on this listserv.  I've used 
them for several water exhibits in our traveling exhibitions, so renters 
only have to do water changes every 2 weeks - 2 months, depending upon 
how many visitors hands etc. are in the water.

They come in a variety of sizes (and thus wattages for the UV bulbs). 
 The UV bulb is inside a quartz sleeve, and as the water flows by (on 
the outside of the quartz sleeve) the bacteria get "zapped."  Some UV 
filters are totally separate units that only do the UV, some are part of 
an all-in-one unit with other media in them.  I"m sure you can spend 
lots of $$, but the systems I've used have tended to be in the $200-300 
(US) or so price range.  Most are really made for pond use.

 I've put them in line with the exhibit's water system, but I have also 
seen other exhibits with a separate loop (and small pump) to circulate 
water from the reservoir through the UV filter and back again.  Some of 
them have "wipers" you can pull to keep the quartz sleeve clean (really 
an O-ring on a rod), if you've got an exhibit with cloudy water (pearly 
tracer) for instance that might coat the quartz sleeve, or really hard 
water perhaps.

The bulbs need to be changed every year (or less often if they're not on 
24/7).  

A cartridge with carbon in it in the plumbing system will also help to 
keep the water clearer, less likely to turn yellow; that needs to be 
changed monthly.

Kathy Krafft
Exhibitions Curator
Sciencenter
Ithaca, NY

Ian McKibben wrote:

>ISEN-ASTC-L is a service of the Association of Science-Technology Centers
>Incorporated, a worldwide network of science museums and related institutions.
>*****************************************************************************
>
>Does anyone have a Water Table type exhibit and if so, are you subject to
>Health Dept. regulations for swimming pools and spas? What type of
>procedures do you use to assure clean and safe water in the exhibit?
>
>Ian McKibben
>Exhibit Developer
>ExplorationWorks!
>
>995 Carousel Way
>Helena MT, 59601
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> 
>
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