It's Back! Tank Flushing Tests in the Clear RV Black Tank

[TheFitRV_James]

The Clear Black Tank Simulator rides again!



Check out the latest experiment here!

First, a big thanks to everyone on this forum who suggested improvements and changes in my experiment setup and methods. I incorporated some of the main ones, and I think it's a much better test for it.

In this experiment, I'm testing four different tank rinsing solutions:

The Sewer Solution
The RV Hydroflush
The Flush King (simulated)
The Tornado Rotary Tank Rinser

I can honestly say I was surprised by the results. Not quite "shocked" but certainly surprised at how well and how poorly some of the products worked. You really just need to see it.

The video is very long - over 25 minutes, and I'm sorry about that. But I go through four whole runs, and I honestly didn't feel like I could cut any more without taking out something important. So perhaps just pretend you're watching a TV show...
A TV show about fake poop...

Before you watch the video, know that it does contain "simulated waste". So, you know, don't watch it during lunch.

I look forward to hearing what everyone has to say about this one. Thank you all again.

[Tinyandthegang]

Been RVing since 1984 and have never rinsed or flushed a tank and never had any problem.

[Turtle_n_Peeps]

TheFitRV James wrote:

bsbeedub wrote:

Turtle n Peeps wrote:
Ok, I have a question for you clear elbow flushers.

Why? Who cares if it's clean or dirty or in-between? I don't get it?

And if you get perfectly clean drinking water out of your tank do you get depressed the first time someone uses the bathroom? :B :E

Because that stuff left over builds up over time and it just might make things worse than they really need to be. A half hour or less longer to clean is no big deal to me. That's my story and I'm sticking to it.

OP here. This last answer gets my vote. In every test I've run - something gets left behind. It makes sense to get as much of it out as you can. Maybe not such a big deal if you're actively using the rig (because yes, you'll just fill it again). But much more important if you're going to put it away for a while.

Along with that, leaving water in the tank... very important.

Glad people like the videos!

I guess I still don't get it but that's ok.

The other day I just had to replace my water valve in my toilet and when it was out I took a peek. Not spotlessly clean but not like concrete either. (Like I heard some people say on this site)

No troubles ever and like I said before, I don't really care if there is 1 oz left or 1 lb left. In about 2 flushes there it is again; contaminated.

When I'm on vacation, I'm on vacation and I don't really care if my poo tank is spotless or not. As long as it holds my poo and dumps when I open the valve that's all I care about. 🙂

[bpounds]

willald wrote:

bpounds wrote:
I tend to think that, as far as rinsers go, nothing does a better job that just driving the rig with half full tanks. Then dump before the mud has a chance to settle out of solution.

Perhaps, but that approach isn't very realistic or possible unless you are lucky enough to have a sewer drain/cleanout at the house or where ever you store your RV. How/where are you going to dump when you get home from a trip?

Not only that, but it'd be kinda tough to test that theory out, with the simulated tank used in these tests. 🙂

Will

It's very realistic if you do at least some boondocking, or even partial hookup camping. Just head home and find a dump station on your route. And you don't have to do it every time. Just do it that way when you can. Just like rinsing, you don't need to always do it.

I agree with you that it would be difficult to simulate as a test. It would be easy to setup the tank in a truck bed, with a GoPro camera and watch the agitation. But I don't think this simulated waste formula will work properly.

[willald]

bpounds wrote:
I tend to think that, as far as rinsers go, nothing does a better job that just driving the rig with half full tanks. Then dump before the mud has a chance to settle out of solution.

Perhaps, but that approach isn't very realistic or possible unless you are lucky enough to have a sewer drain/cleanout at the house or where ever you store your RV. How/where are you going to dump when you get home from a trip?

Not only that, but it'd be kinda tough to test that theory out, with the simulated tank used in these tests. 🙂

Will

[bpounds]

I tend to think that, as far as rinsers go, nothing does a better job that just driving the rig with half full tanks. Then dump before the mud has a chance to settle out of solution.

That could be one of your future test vids.

[2gypsies1]

We have a tank rinser which we let rinse for about 5 minutes. Then we dump a couple buckets of water down the toilet and hopefully it gets out most of the excess crud, especially at the bottom of the toilet pipe. We've not had problems in 10 years so it seems to do it's job. When finished we close the valve and dump another bucket of water in and we're ready to 'go'.

Also, we don't use any chemicals in the tank - only water, and never any smell.

[willald]

Thanks so much for listening to the suggestions, and running this second round of tests based on the suggestions.

For the most part, your conclusions and what you found are exactly as I would expect - No matter what some folks say or what various marketing suggests, You simply can't beat a tank flusher for how well it cleans out the tank. The Flush King (or Hydro Flush with a valve) comes in a close second.

No surprise at all, that the hydro flush without a shutoff valve was useless. I figured that from the first time I looked at those devices.

I would only add the following to your conclusions:

conclusion #2: Clear section 'lying' about how clean tank really is.

Yes, when pushing water into the tank, what you see in the clear piece tells you nothing of how clean the tank itself is or is not.

HOWEVER, when draining the tank (or draining out water you pushed up in there to flush), what you see coming through that clear piece is very indicative of how clean your tank is or is not. That is where the clear piece is very useful. I have always used one for this purpose, 'cause without it, you never have any idea how clean you have got the tank.

A clear piece actually is a very useful tool for flushing/dumping, as long as you know when to pay attention to what its telling you, and when not to.



Conclusion #4: Drain-end flush systems no more effective than filling tank through other means.

Agree 100% with this. However, for those of us that:

A. Don't have a sink that plumbs into the black tank.
B. prefer to do all the flushing/draining 'activity' outside at the drain hose instead of treking in and out of the RV bathroom
C. Hate the idea of dragging a water hose and/or tank wand into the RV

..In these cases, a drain-end flush system (with a valve) is a very useful, effective way to push water back up into the tank to flush it out.

One other note: You do not have to spend the $$ for a Flush King, to get a clear piece with a valve and water line connection. Camco makes the Dual Hydro Flush that is almost identical to the flush king - Has the clear piece, water line connection with backflow preventer and a shutoff valve to force water up into the tank, and it costs somewhat less than the flush king ($26 vs $49).

This (dual hydro flush) is what I use on our present RV, and it works great. IMO it is next best thing to a tank rinser, and these videos confirm that. I would prefer a tank rinser, but don't have one on our present RV (nor is it built to allow installing one, or I would have a long time ago). Our previous RVs all had a tank rinser, and my next one will as well.

Also, with regards to tank flushers: The tornado rinser used in this test, while it worked great here, due to its moving parts (rotating head), it is known to quit working after a while (head quit spinning, and getting jammed up as a result). The traditional 'quickie flush' units that do the same thing but don't have the rotating head, are a bit more reliable. I'd prefer one of those over the tornado flush, just 'cause that is one part that once installed, I don't ever want to have to remove or mess with again, haha. 🙂

[Travels_with_Yo]

cross country wrote:
Great stuff! Now I wonder what the "empty" tank would look like without a three foot drop at the dump? Many hook-ups require a 20 foot run with a bump up to accommodate the elbow connection into the drain pipe. Some drain pipes are above ground level exasperating the condition for good draining.

The point is simply this; with a 6 inch drop over 20 feet of slinky and then a bump up...causing back up and only the pressure of the tanks contents, would the results of the tests be basically the same?

Would there be so much left behind that only continuous filling and flushing could be performed to clean the tank?

Could this by why so many are aggravated in dump line ups? Straight pipes 2 feet up simply drain more efficiently than low valves with numerous elbows?

Cross Country has a very good (and important) point. The first thing I noticed was the fact that your tank, being about three feet off the ground creates significantly more "head pressure" (see how water pumps work) which has a big influence on the discharge flow rate. This flow rate largely influences how much or how little debris is left behind. I also think that your additive test (breaking down the waste) will make the first set of tests pointless other than showing how the clear sections appearance can be misleading.

I still appreciate your time and effort though to enlighten and help the community and I look forward to the additive test videos. I also think the experience of long time RVers who use detergents of some sort and agitate them while traveling between stops is excellent information.

[rolling_rhoda]

Thanks, James! I enjoy your website and blog. Thank you to you for sharing your stories and info.

[TheFitRV_James]

bsbeedub wrote:

Turtle n Peeps wrote:
Ok, I have a question for you clear elbow flushers.

Why? Who cares if it's clean or dirty or in-between? I don't get it?

And if you get perfectly clean drinking water out of your tank do you get depressed the first time someone uses the bathroom? :B :E

Because that stuff left over builds up over time and it just might make things worse than they really need to be. A half hour or less longer to clean is no big deal to me. That's my story and I'm sticking to it.

OP here. This last answer gets my vote. In every test I've run - something gets left behind. It makes sense to get as much of it out as you can. Maybe not such a big deal if you're actively using the rig (because yes, you'll just fill it again). But much more important if you're going to put it away for a while.

Along with that, leaving water in the tank... very important.

Glad people like the videos!

[bsbeedub]

That stuff left over builds up over time and it just might make things worse than they really need to be. A half hour or less longer to clean is no big deal to me. That's my story and I'm sticking to it.

[Big_Katuna]

Because in Floridas heat I don't want it to stink.

[Big_Katuna]

For years with my non- rinser installed RVs dumped and then had the DW pour a pot of water in and be done. The DP came with a Tornado. I bought a clear ext. After I dumped and started seeing how much stuff kept coming out after I started closing, filling and dumping and repeating, I changed my technique. I use a wand down from the top sometimes too.

I also read in the Fleetwood owners manual to always add five gallons to the clean tank after dumping which I do.

[TechWriter]

I have a "washer" built into my black tank. To clean the tank, I just close the black tank valve then use the washer to fill the black tank with fresh water. Drain the tank and repeat.

Only had one overfill when I first tried this method.

A rising tide floats all ...