Well, if your black tank smells bad, chances are, sooner or later, your camper will smell bad, too. I speak from experience, back when all I used was the expensive chemical stuff sold in RV stores, and it didn't work worth a squat. Since using my "sewer juice" and ice - no further problems. If I've damaged anything by using the homemade mixture, it sure hasn't shown up yet after 3 years or so.
2003 Ford F-350 V-10 Crew Cab 4WD Long Bed
2004 Jayco Designer Medallion 29 RLTS 5th wheel
Bill, Gayle, and Mindi (dachshund)
Retired at last !
Nothing is foolproof to a sufficiently talented fool.