surface film and snails

The surface film disappeared after raising my sump height and thus the output flow of the water from the pump back into the turtle tub. I also repositioned the cork in a way to have minimal impact on the clockwise flow of the water (helping maximize surface disturbance). Also, I did a mini experiment and placed some cork into the guppy tub to see if film developed. Still there was no film in the guppy tank. I still don’t really know where the film comes from but seem to have eliminated it. Chun, I was looking at some of the natural history sites linked on the Diamondback Terrapins web site. At least one of these sites, mentioned that the diet of diamondbacks consists mostly of periwinkle snails. I’m sure they are easy to find in marshes and other brackish systems but they have a rather thick shell (much thicker than freshwater snails)… I guess it is no wonder that terrapins develop such large beaks. I wished that I knew more about terrapins in 97-98. I had the opportunity to work as a marsh ecology technician for the Univ. of GA Marine Institute on Sapelo Island a barrier island off of Georgia. The only access to the island was and is by ferry. We had huge expanses of pristine saltwater marshes and estuaries and probably terrapins in the more brackish areas. Cheers, Kurt