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Well, at the risk of becoming known as “Professor Poo” on the internet, I’m going to continue…
The response to my first Black Tank Simulator experiment has been enthusiastic and the feedback plentiful. Thanks to everyone who took the time to sit through the video and provide suggestions. Some suggestions, like putting nail clippers through the tank, I probably won’t try. But I’ve spent the week gathering the feedback, thinking through changes I can make, and planning future experiments.
First – here are some of the suggestions that I’m going to incorporate right away.
Tank cover and venting
Real black tanks aren’t open at the top, although they should have a properly functioning vent. A few of you suggested that the reduced inflow of air from a vent stack would have affected the results. I don’t necessarily agree with that, but, since I obviously needed a cover anyway, I’ll be including a vented cover in all future runs. The vent stack in my own RV used 1½ inch ABS pipe, so that’s what I’ll be going with. The cover will be clear, of course, and removable so that we can easily see inside when the job is done. I’ve already started working on this, as you can see below.
My intention with the original toilet paper cut into strips was to hasten the decomposition to get the tank into a “used” state. But as many of you pointed out, toilet paper doesn’t go into the tank in uniform small strips. I’m sure we’ve all had to dump shortly after adding new material to the tank, so in future runs, I’ll be adding some wadded up, folded, and torn TP to the tank in addition to the strips.
Some of you asked questions like “what order was material added to the tank?”, “what was the temperature of the tank material?”, and “how long between filling and emptying?” While I tried to keep things consistent, these were questions I didn’t have the answers to. In an effort to make the tests more uniform, going forward, I’ll prepare and make available test sheets – which will list the steps and the observations.
Many of you wondered about the very high water pressure I seem to have at the house. 120 psi is more than most can realistically expect, and quite reasonably, may have affected the results. I don’t want to hook my standard pressure regulator inline with the tank (even though it’s just simulated waste, and there are backflow preventers). But, in future experiments that call for fresh water, I’ll use a pressure regulator. I plan to buy one of the inexpensive regulators marketed for RVs, and use that one exclusively for future experiments.
When I built the simulator, I realized I would never be able to make everyone happy. Each RV has a unique waste plumbing configuration of straight pipe, elbows, and wyes. Knowing this, I opted for the simplest configuration, and hoped everyone would be able to extrapolate the results for their rig. However, on testing, it’s rather obvious that a straight shot back into the tank creates perhaps unreasonably favorable conditions for a pipe-end flushing system. So, for future tests, I will be hooking up a pair of 45 degree elbows when I use a pipe-end flushing system. This will prevent the straight shot back into the tank, and, since I can buy the clear twist-lock ones, I won’t have to dismantle any part of the rig.
Now, on to what to do next. I’ve created an online poll right below where you can vote for what you’d like to see in future experiments. You can vote for more than one option that interests you. I can’t promise that I’ll tackle them in order of popularity, but this may keep me from spending time and resources on something that isn’t of interest to anyone. Brief descriptions of the experiments are just below the poll
Comparing the effectiveness of tank additives:
For this experiment, I propose to test three different tank additives (and no additive at all): A standard, toxic “blue stuff” additive; an enzymatic additive; and the oft-mentioned GEO method. I would add the simulated waste incrementally over three days to give the additive opportunity to work. I would not agitate the contents of the tank prior to dumping. Each test would conclude on the fourth day with dumping from a standard 3 inch hose. I would need to find a way to store the partially full tank for several days in controlled conditions – and then a way to move it over to my sewer cleanout – to make this possible. Due to the nature of the test, it would take a couple weeks to run.
Testing the dumping action of a macerator:
In most respects, this would be similar to the last test of the Sewer Solution. I would test a macerator pump and compare it to the standard 3” hose. As neither a macerator nor a 3” hose come with a tank flush as standard, one would not be used. The expense of the macerator would be one downside, unless I could obtain a manufacturer sample. This would also require pulling a 12v battery with adequate capacity from somewhere to power the macerator.
Testing the conventional wisdom:
For this test, I would propose four runs to test the effect that tank fill level has on emptying solids from the tank. This would require filling the tank ¼, ½, ¾, and full – with proportional amounts of solids – and then dumping through a standard 3 inch hose.
Testing various tank flushers:
The intent of this test would be to compare several tank flushing methods for their effectiveness at removing remaining solids from an emptied tank. I propose to test three flushing methods: the RV Hydro Flush pipe-end flusher, the Sewer Solution, and the Tornado tank flush system. For this test, I would utilize the clear elbows and regulate water pressure as previously mentioned. I realize that there are several flush protocols I could test, but to keep things consistent, I would select a single flush procedure (e.g. flush continuously for 5 minutes, then dump all remainder) to test.
In depth with the Sewer Solution:
Finally, I’ve received a number of comments and questions on the Sewer Solution. I could go more in-depth with this particular tool and test things like: how much fresh water is used at various pressures, the effectiveness of various flush/dump/flush protocols, maximum effective vertical pumping of sewage, etc. I would need to solicit tips from experienced Sewer Solution users to make this a more effective segment.
Well, there you have it. Those are the experiments I am considering running next. Think about it, and vote for those that you would like to see. I will leave the poll open for a few weeks to give everyone a chance to weigh in. In the meantime, I’ll finish up making my lid and vent stack. I also hope to do some actual RVing too!