Some people use the same stuff as what's used to inoculate septic tanks. But that won't necessarily help cut any odors, and most of us use regular RV black tank treatments, and most of the ones commonly found work just fine. I highly recommend that you stay away from those that use formaldehyde, though. That just kills the microbial action and can befoul RV park sewer systems anyway.
I've used Happy Camper before and liked it, but it can be hard to find.
These days the non-formaldehyde versions well-outnumber the formaldehyde ones out there, so it's relatively easy to find "green" or "eco-friendly" treatments; just read the labels - the good ones will usually tout the fact. I shop for the ones that are on sale, but tend to gravitate toward tried and true Thetford products - used to be Aqua-Kem Green but I think its now called Ecosmart. Regular Aqua-Kem is formaldehyde, so don't confuse them.
Dometic, Walex, and Travel Jon all make many bio-friendly products that work with enzymes to break down waste. Some use additional fragrance to kinda cover odors up a bit, and there may be some that are fragrance-free. Some smell like citrus, some floral - we prefer citrus. My wife isn't overjoyed if I bring home liquid versions though, as she finds the drop-in packets much easier to use, and I've come to agree.
They can come in little buckets, but we really like the ones in zip-lock bags because they store just about anywhere in a cabinet and seal up good; you don't want moisture to get in the package or the packets can disintegrate, so we squeeze the air out, zip, stick on the narrow shelf in the cabinet behind the toilet, and forget. Thetford's Ecosmart 12-pack Toss-Ins are a good example and what I usually buy on sale.
Walex makes a 10-pack that's cheaper, Blue MAX, which I guess is fragrance-free but we like the Ecosmart citrus. Walex Bio-Pak and Porta-Pak are scented 10-packs that are options we haven't tried either. You'll just have to examine the packages in the store (Camping World has as many choices as any) and come to your own conclusions, depending on your personal preferences; just try to stay away from formaldehyde ones.
Joel
