| Carl, when I looked at the drawing it did not occur to me that there is no skimmer. However, without one you can get a persistent layer of scum on the surface. The scum is dissolved proteins and other long-chain molecules that affect the surface tension. The scum may be colorless, but you notice a difference in the "texture" of the water surface. The bakki shower splashing may partially break it up, but its a long pond and the splashing may not be enough. Adding a skimmer would complicate matters if you want to stick with a vortex for each drain. Its difficult to simultaneously run a bottom drain and a skimmer to a single vortex becuse you can never get the flows equalized. Maybe you could alternate between having a single vortex draw from the skimmer for a while and then draw from the bottom drain.
-steve |