here on the high desert plateau you'll get a good kick out of evaporative cooling
its well worth doing even as a precooler for a phase change condenser
"bong coolers" where never very effcient designs simply easy to make
(forced draft generally without a fill)
you do far better with traditional swap cooler or industrial evaporative chiller designs
adapted to your scale
http://www.google.com/url?sa=t&ct=re...e93SisWSCPMp8g
http://www.cti.org/cgi-bin/download.pl
http://www.airah.org.au/tec_inf.asp
decent modern packing\fill would drastically increase the interface