Dave the best way to explain it is for you to do an experiment at home. Take a milk jug full of water, and then add several drops of food coloring. Check the dispersment the following morning. Keep in mind that ponds naturally get darker the deeper they go.
ML- the coloring does not effect good plankton because usually it is this "surface" plankton that use photosynthesis for carbon dioxide to oxygen transfer. Photosynthesis does not occur at the bottom of the pond unless you have COMPLETE clarity of the water. If this is the case, then you usually have a weed and algae problem starting so you are back to square one trying to fix things. Kinda like the saying that reads, "An ounce of prevention...". We have never had an issue with the fry (or minnows for that matter) being affected. My guess on this (and it is only a guess) would be because these smaller fish stay shoreline. They generally do not travel deep. Plus the added benefit of this dye is that it is non-toxic. It is a form of highly concentrated food coloring.
This has just what has worked for us guys.
By the way, it also makes your water nice looking (from a woman's point of view)!
Deb
