interestingly enough, according to NC State University :
"Are Septic-Tank Cleaners Necessary?
No. These products include biologically based materials (bacteria, enzymes, and yeast), inorganic chemicals (acids and bases), or organic chemicals (including solvents). They do not reduce the need for regular pumping of the septic tank. Some of these products contain organic chemicals and may even damage the drainfield or contaminate the groundwater and nearby wells."
taken from this link for a RV holding tank, installing a tank flusher is a far better way to handle the issue
Jim