Black Diamond Stoneworks GET SERIOUS RV,Boat,Camper Chemical Toilet Holding Tank Treatment&Deodorizer.Works Faster Than Tablets or Packs in Grey&Black Water. Concentrated with Stress Relief Fragrance

I have used a handful of brands of black tank treatments on my RV. Including some of the RV favorites, and this is just as good (if not better) in some cases. Not only does it prevent odors from escaping your toilet, but has millions of hungry bacteria that turn your waste into liquid. Even after just using the toilet less than an hour before dumping. Another plus is it is supporting a US based local company. I recommend this to all RVers.

4yr Update:After 2.5 years of full-time RV living, I quit using any and all black tank products for another two years of RV life. Like many other experienced RVers before me, I didn't notice any difference. My last two years of RV living, I was in a better location for flushing out the tank, living with full hookups on a large riverfront private lease in the mountains. Flushing the tank once a year with a good hose nozzle produced far better results than using tank products. In my experience, black tank products are a waste of time and money if you can rinse out your tank once a year or maybe more in hot regions.2yr Update:This seems to work better than Campco, Happy Camper, and the blue stuff, at maximum strength for all four. Waste seems better dissolved and there is less odor with this product. If you have to dump using a portable wagon, there will be odor no matter what. The stink jets through the air vent. You would probably need to use an industrial odor mask in large quantities to completely mask 40ga of undiluted sewage. Regular sewage has all the gray water mixed in; so keep that in mind.This product seems to reduce this odor better than the others. I bought a gallon. I experimented with other products and I returned to this product.I also put the product into a spray bottle and regularly spray the toilet and drains.Happy Camper (Amazon item) claims that it works better and is cheaper than any other tank products. I took the trouble to do the math and share it with you:(2021 Amazon prices)Happy Camper:Small container:$24.4518 treatments= $1.41/scoop!9 treatments (label max) = $2.80/2 scoops!Bigger container:$49.45/64 treatments = $.77/scoop32 treatments (label max) = $1.55/2 scoopsBiggest container:$86.45/130 treatments = $.67/scoop65 treatments (label max) = $1.32/2 scoopsBlack Diamond1ga container (128oz):$29.88/128 treatments= $.23!64 (label max)= $.47!Me: (liberal use exceeding label) 52= $.57 (still less than one scoop Happy Camper at largest bulk price)So, you get over a year's worth of treatments at label maximum with one gallon of Black Diamond, at a significantly lower price, and (possibly) with marginally better results.Important: You have to wash the tank out periodically, with water pressure. Otherwise, sludge will build up and you could develop a stinking "pyramid" directly under the toilet hole. That pyramid can stay above the water line and cause terrible odor. Some product isn't going to solve this.Also, cut off your water and open the toilet valve. Use a bright light. You will probably see sewage buildup going all the way down to the tank. This has to be cleaned if you want to eliminate stench. None these products are going to prevent nor eliminate this.This is why people are saying these products didn't work. The product manufacturers may leads you to believe otherwise, but in fact you must perform periodic cleaning with water pressure and you may need to scrub the drain. The more the tanks are used, the more this will be true.No matter what the RV industry (or boat industry) suggests, proper use is complex and challenging. If it isn't, you're doing something wrong and the consequences will be expensive and unpleasant.Original review:This is comparable to other products, but claims to have a microbial instead of chemical or purely enzymatic active ingredient. I have only used this in winter, in a northern US latitude, so I cannot say how it will work on smell in summer heat. Presumably, microbial growth would increase with warmer temperatures. (Update: Reached 109° here. Worked the same as in winter, from my perspective. Like all of the others, I am certain that there is a strong industrial scent in Black Diamond doing most of the odor masking. However, it seems to dissolve the waste and paper slightly better than Happy Camper. I am probably using 3oz [rarely 4oz] vs the 2oz recommended max of 2oz BD. My tank is bigger and has had few proper clean-outs, to date. Happy Camper does take up less storage space.)I was hoping it would clean the holding tank level sensors, but so far (2 dumps) it has not. Neither did Happy Camper, nor two other commonly available treatment products. Two dumps is premature to ask for a review, but I am responding to an Amazon request for a review. It's probably still establishing a tank biome. My thoughts are that if it works at all, it will work better over time. (Update: Never did clean the internal sensors, 2yrs later.)I have not compared the price per treatment of this vs Happy Camper. (Update: Roughly the same.)

Does the job, wish it had a air freshener type smell

This is the best product I have found for keeping the black tanks odor-free and flowing.

After being an RVr for over 40 years and using most all the common and usual brands, disappointed by most of them, I tried Black Diamond. Wow . What a difference ! NO odors, NO product coloring that causes stains, and most of all NO JAMS OR BLOCKAGES - EVER. Black Diamond eliminates any solids and reduces the waste to an odorless liquid which readily washes away. I will never buy anything different. Simply amazing.

NOT THE BEST ON THAT PRICE RANGE

This is the best black tank deodorizer &treatment we have ever used. It is long lasting, not having to add more all the time, once used, then in about a week, time to empty and begin again.

Product didn’t work. My house boat toilet still smells awful. I bought 2 gallon sized ones and a quart sized one. Very expensive. Just made me sad that I thought I was getting the best money could buy. I literally spent the last of my money for a let down. Also I did pump out my tank and then put this stuff in with water, so I know how to use these products.