Happy Camper holding tank treatment

you can flush your tanks all you want but you'll never get everything out, especially all the oils in the grey tank. I've tried flushing for 45 minutes or more, tried the calgon and dish soap, even tried an overnight bleach soak. Nothing seemed to work until I tried happy Camper. Granted it's only been two trips so far. Also I walked in my grandfathers rv this weekend and the smell in the camper was horrible. I asked what happened and they said it come out the toilet when they flushed. The had camped for two days prior. I dumped their tank and put the happy camper in and literally a couple hours later they hand no more Oder. **** I'm starting to sound like I sell this stuff. Really though just trying to help a brother out. I wish Someone had recommended it to me sooner. It's not sold around my area so I had never heard of it until I went picked up my tc in Oregon. That's what the manufacturer recommended.