Sewage treatment

Any opinions/advice on liquid Thetford (or otherwise)sewage tank treatment as opposed to tablets, or the packets of chemical I just purchased?

Formaldehyde is used as a preservative.  Why preserve that stuff.  I have ran into campgrounds that have their own septic tank and they say not to use that stuff.  It keeps the sewage from from braking down in the septic tank.

Terry 

We have gone to the "green" stuff, and it seems to do a fine job, as long as it's not very hot (like high 90's or above for a week or 2). But if you're like most of us, you are dumping the black tank every 2 or 3 days while you're on the road anyway, so I don't see any need for some super duty tank treatment that lasts for weeks on end. Just try a few different brands and see what works best for you - besides, it gives you an excuse to go camping under the guise of "scientific research" 

We use the drop ins. Been happy.

Most of our trips are under 4 days, and we do use the campground facilities when convenient/nice, so often we may not dump every trip because we are not full. We dumped this weekend, and that was the first dump of the year. 4th trip.

My dad has had a home dump station since about '75, back before the green question came up.. I recently asked him if it ever bothered his septic, either chemical or just the volume of dumping in +60 gallons at once, and he said no.. but he also said that since the non formaldehyde stuff came out, it's all he has used. I am getting ready to add a dump station here at our house, and was a bit worried, but all of the info I have been able to find says no problem.