Ditto on Peggy's book. We stuggled with ours a bit - turned out that the vent to the holding tank was partially blocked and the loop on the bidge pump was excessive, causing alo of backflow
This is the answer folks.... if the bilge smell like poop or diesel then you have bigger issues. I have a diesel engine and 2 heads that we happily do our #2's in and the boat and bilge don't smell.... except for the smell of the ocean breeze!!If the odor is diesel or sewage - something needs to be fixed not cleaned or covered up.
If the odor is mildew or "musty", spray and wipe with this inexpensive home-made mildew cleaner top rated by Practical Sailor. It doesn't stain or smell. The ingredients are very safe (they all are used in food products). If you mist a coat on after cleaning and let it dry it will retard mildew coming back. (and getting a dehumidifier will help even more) :
1 quart hot water
2 tablespoons baking soda
2 tablespoons Borax
1 tablespoon TSP (available in the paint aisle at a hardware store)
Damage cabinet finishes and things that are plastic.ozone generators