Re: Aquatic Plants Digest V1 #385, Gels

"Gels" are not plastic. They are UV tolerant dyed sheets of gelatin! The
originate in the Theatre trade, and are used to filter theatrical spot and
flood lights to give whatever color is desired. Gelatine is used because it
will neither melt nor catch on fire from the intense heat of the lamps, and
plastic will. They are quite (understatement!!  :) )sensitive to the idea of
fire in theatres.