Nasty Subject

[Grandpa]

There are lots of chemicals on the market to treat black water. Has anyone had better luck with one chemical over another? We've tried several and none of them seem to eliminate that poof of nasty that comes up from the tank when you flush.

[TravelinAnderson]

There's a product that a lot of RVers like named RV Digest It. I've never used it but have read some good reviews about it. I have used the Geo Method in the past and it is a good way to clean and deodorize your black tank.
We've been traveling full-time for 9 months and in our 36FL for 5 months and haven't had a black tank odor issue while we're camped. If we do in the future, I'll use the Geo Method.
Some things to remember about the black tank is that it is a holding tank, not a septic tank so solids aren't usually in it long enough to really break down. I would think chemical additives do little more than act as a deodorizer. Just my opinion.
Another thing...don't empty the black tank until it is almost full... I've seen people at full hookup sites with all their drain valves, including the black water tank, in the open position. It's ok to do this on the gray but not for the black tank. You need a lot of water to move that stuff out.
Also, if your exhaust fan is running, especially if it's a Fantastic fan, when you flush the toilet you may get some odor. The fan moves a lot of air and the gap at the bottom of the door may not be large enough to provide it with an adequate air supply so when you open the toilet valve it will pull air up from the black tank. We've even noticed some odor in the bathroom when we move to a new campground if we forgot to close the bathroom vent.
That's all I have for now... sorry if it was wordy.

[timmytfl]

Great info about that Geo Method! I'm going to keep it for future reference.

[Grandpa]

Really good information! We are headed out this weekend and will give the Geo Method a try. We do have the MaxxFan and it's usually running full blast in the bathroom during that time. We'll turn the fan off prior to flush to see if that helps.

I don't see individual tank vents on the top of my 36RL. Do the tank vents dump into the vented attic on the unit? Is there enough air movement to pull the odor out of the attic?

[TravelinAnderson]

I can't say on your 5er but all my waste tanks are vented. If you meant is there enough air movement with the fantastic fan running to pull air from the black tank vent the answer is yes.
That's been my finding anyway... your results may vary.

[Grandpa]

Actually, my concern is the venting of the tanks into the 'attic' space of the roof. There is a vent at the front of the unit and one at the rear. I'm questioning if there is enough air moving from one attic vent to the other to pull the odor out of the tanks. I don't see any vents for the individual tanks.

The MaxxAir fan in the bathroom will suck you off the toilet if it's on high! No problem with it at all!

[TravelinAnderson]

I don't they are designed to remove odor from the waste tanks. I believe their purpose is to prevent pressure from building up in the tanks and to provide a vent for when you drain the tank. Otherwise it could create a vacuum that would restrict the water flow. Imagine emptying a gallon of milk by turning the jug upside down. Without a vent it will gurgle, a vent would allow for a steady, forceful stream. That is what flushes the solids from the tank.