Thanks Bill! There is never-ending amount of detritus in my pond basin. However I do wonder if the PK shrimp like a certain type of leaf structure over another (we have settled out iron on a thick layer of mostly oak leaves, a black nasty mess) Did you uncover any info on the calcium content of water (hardness) and their preference to thrive?

If I could get cockroaches to grow gills I'd be happy to stock them by the millions as long as my organic debris thins out and as long as they don't mind the YP or PS snacking on them. Could you put them in an inverted bowl (like a diving bell or bubble) with O2 supply but have the bottom of the bell open to the bottom of the pond and let the cockroaches go to town?