No question, Thedford's AquaKem Original is the best. Yes, it contains formaldehyde which IS biodegradable. Yes, it works, zero odor.
Don
I also use Thetford's chemical containing formaldehyde and have been for many, many years. BUT...I learned something from your comment. I use Campa Chem in the powdered packets and buy from WalMart. I did a little research and here is a reply from Thetford when someone asked about the difference in the two. I was under the impression that Campa Chem was the only Thetford product using formaldehyde.
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Hello,
Aqua Kem and Campa Chem are almost identical products that use almost the same formula. The Campa Chem is a more economic version of Aqua Kem and is often used in smaller products such as our Porta Potti's. Aqua Kem is a more concentrated version that is often used in RV's which have much larger holding tanks since our Aqua Kem starts working within 30 minutes. Both can be used on smaller units or in RV's however so when purchasing, it will really come down to which ever one you would like to use.
If you have additional questions, please contact us.
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I figger that Thetford employees chemists and should know what is good and what is not good for the environment.
I'm on several RV related blogs, including Facebook, and the RV toilet seems to be the most popular subject. On one Facebook page, I found what I thought to be some really weird ideas about what to put in the black tank. So, I posted that I worked at a mortuary and put embalming fluid in my black water tank. I received a couple of posts warning me of the dangers. I thought my comment was so ridiculous that readers would see through the sarcasm, but no.
From what I read, Happy Camper seems to be the most popular RV chemical and receives rave reviews. For me, I will stick with Thetford.
Cheers

Barry T