Chad,
I have also been told at times that Bottom feeders don't add to the bio load, This of course is an incorrect statement, and as near as I can tell this is where the confusion comes from. There are many aspects of bio-load, one of which is Oxygen level in the water. This is where the surface area calculations for stocking come into play. The greater the surface area, the better the gas exchange, of course there are many other factors that play in as well but surface area is significant. Bottom feeders are often considered exemt when figureing stocking based on surface area, this may be at least in part accurate, because they tend to live in the less oxygenated areas of most tanks and are less demanding of high oxygen levels. They still contribute waste which adds to the ammonia cycle, therefore they do ahve a true effect on the total bio-load. In the case of ghost shrimp, they truly do have an effect as well, but they produce smaller amounts of waste than a fish so you can stock many more of them and have equal or less effect. As far as the bottom feeders, My recommendation is pick out two or three that you like the looks of and then see which one fits your tank specs the best. I like Pictus cats, but I've been told they like to eat Tetra's
