Hello and thanks to all in advance!!Going to use this apparatus for first time in order to clean out my black tank, do I also clean out the grey tank? When flushing, do I have just the black tank valve open or both valves? I will assume that the flush king stays in the closed position until the process is done? Finally, how long should I flush? My apologies if questions seems silly but I just want to get it right. I have a 2003 R-Vision trail lite travel trailer. Thanks a million and Happy New Year!

They make clear plastic connections that will hook to the black tank output so you can see what's flushing out. Flush until clear, but don't get too hung up about it, it's not that big of a deal. There are people that never flush their black tank, after all you're just going to get it dirty again. The main thing to do is empty it before storing it. You can flush it then.Use lots of liquid in the black tank so everything flows easily when emptying it. If, boondocking, you can do your dish washing in a dish pan and put the used dishwater down the toilet to both save room in the grey tank and put more liquid in the black tank to help everything drain well.Bill

I have one. I don't worry about back flushing the grey tank. Only the black. It is useful when your grey fills and you're boondocking. You can flush some into the black. But I see no advantage when you are hooked up to back flush the grey

I have a generic version of the Flush King and use it all the time. Here is how I do it, and I have found this is probably the best method. As stated by the previous poster, you do not need to flush out the gray tank. I'm assuming your camper has 2 tanks and both tanks drain into one outlet. Each tank has it own release valve. Here's a set of photos of my camper and "reverse flusher" and how I use it. I think you will find this the most effective too. After doing it the first time, it won't be so confusing. I lettered the 3rd photo to make the steps easier to follow. I'm also assuming your Flush King comes with the clear section. This is really the most important part of the system, so you can see what is coming out and when it quits draining.Here is the same photo with a lettering system to identify each item:Valve A is the Flush King valveValve B is the Black tank valveValve C is the Gray tank valveItem D is the garden hose and the twist knob to direct the water from the hose up and back into the tanks, down the drain hose only, or completely off.To start this process, you need liquids in both tanks. The more you have in the gray tank, the better this works. Also, you really do not need the garden hose at all. It's not necessary, but I'll address that later.Attach the "Reverse Flusher" and close all valves.First, open Valve A (Flush King valve)Second, open Valve B (Black tank) and let the black tank run until it's empty. You can see when it's empty because of the clear section. You can also see the contents coming out. You'll be surprised what happens next!Third, when the black tank ends, close Valve A (Flush King). Leave Valve B open (black tank), and open Valve C (gray tank). Because the black tank is empty, the gray water will force itself into the black tank, filling it with sine if the water from the gray tank. Leave Valve C open for only about 10 seconds then close it. You don't want the black tank contents to flush back into the gray. So, only a few seconds, then close it. The sudden force of the gray tank pushing backwards into the black tank will beat up any remaining contents in the black. The backward rush will loosen everything remaining.With the gray tank closed (Valve C), now open Valve A again (Flush King), and now open Valve B (Black tank) and watch the magic!You'll see a LOT more "stuff" come flowing out! A lot!Once the water and stuff from the black tank stops again, close off the Flush King (Valve A) again, and open Valve C (gray tank) again and let it flush backwards into the black tank (again). Wait 10 seconds and then close off Valve C (gray tank), and open Valve A (Flush King) again and watch the second round of magic! OMG! How much more comes out the second time! YOU WILL BE AMAZED! Who would think you'd get so excited over watching POO! But I bet you will!OK, repeat this procedure 1 more time. Each time you back flush the black from the gray tank, the water level in the gray is getting less and less of course. You do want to try to keep a bit in the gray after the 3rd back flush.After the third, THEN close off Valve B (Black tank), open A (Flush King) and C (Gray tank) to clean out the sewer hose.This entire process does not take very long. And I think once you've done it, you'll do it EVERY time you dump for ever more! Your black tank will never smell and will always be flushed out. You'll never have build up, and you really do not need to wait to dump your black tank if it's not 100% full, like so many recommend. Just make sure you have a lot of water in your gray tank.Now, when does the garden hose come in handy?For those times you don't have enough water in the gray tank to back flush, or if you simply want to reverse fill either tank, or if you flush your black tank and don't have gray water to clean out your sewer hose, you can run the water from the garden hose through the Flush King to clean out the sewer hose. (close both black and gray tank valves if you want to wash down the sewer hose only.I have only tried using the garden hose 1 time in over 15 years of having a reverse flusher. I see no need for the garden hose attachment. The back flush works quite well, don't need the garden hose.As one final step, for example if you are winterizing and want to make sure your tanks are about as clean as they can get, after all the back flushing steps, fill your black tank via the toilet. Let it fill naturally, completely full, until it comes up int he bowl of the toilet. Then flush the black. I do this as a last final step before winterizing. Drain the black tank completely until it drips no more. Then you are ready for the pink-stuff for winter.I hope this help, and hope it makes sense. Like I said, after you've done this the first time, you'll see how easy it really is, and how effective it is also. You won't do it any other way going forward.

Dutch's back flush method works very well. The sudden rush of soapy gray tank water loosens up the stubborn material. However, give the gray tank a few seconds to flush out before using it. Heavy solids (like coffee grounds) accumulate at the bottom of the tank and heavy solids are what you're trying to get rid of.You don't need the extra flush king valve to accomplish this. Simply hold the stinky slinky up higher than the level in the tanks and open both valves. Let the gray water run into the black water for a few seconds (if you have a clear section you can see when it stops), close the gray valve and drop the hose.

jplante4 wrote:Dutch's back flush method works very well. The sudden rush of soapy gray tank water loosens up the stubborn material. However, give the gray tank a few seconds to flush out before using it. Heavy solids (like coffee grounds) accumulate at the bottom of the tank and heavy solids are what you're trying to get rid of.You don't need the extra flush king valve to accomplish this. Simply hold the stinky slinky up higher than the level in the tanks and open both valves. Let the gray water run into the black water for a few seconds (if you have a clear section you can see when it stops), close the gray valve and drop the hose.Ah! You learn something every day! I would have never thought of just simply lifting the sewer hose! Great idea!

Flush King | Good Sam Community

beemerphile1
Explorer
Jan 15, 2016
The only tank I have ever needed to clean is the fresh water tank. I sanitize it twice a year. The black and gray don't need cleaned.
allen8106
Explorer
Jan 14, 2016
I have the flush king also and like the way it works. I've never flushed the grey tank with it but that's not to say you can't or shouldn't. It won't hurt to do if you want. For sure the black tank though. Just make sure you open the black tank dump valve before you turn on the water, otherwise you will pressurize the pipe between the two valves and run the risk of a pipe rupture. I've seen it happen.

I watch the tank fill through the toilet and typically let the tank fill with water until it just starts to come up the pipe between the tank and the bottom of the toilet. Mine is a straight shot down so its easy to see when the tank is full. As soon as I see it's full I go out and shut the water off and pull the valve on the flush king. Works like a charm every time. Just don't get distracted and forget about the water being on. I know a guy that flushes his 140 gallon blank tank like this twice every time he dumps. Does he need to fill up all 140 gallons or do it twice? Likely not but he claims he's done it this way from day one and has never had any black tank odors and he uses no blank tank deodorants or chemicals of any kind.
azjeffh
Explorer
Jan 13, 2016
Partially fill the black tank with your spray washer and you'll accomplish the same thing.
mileshuff
Explorer
Jan 12, 2016
My 5'er has a built in spray washer. I let it run for 5-10 mins then use the flush king once which gets quite a bit more out. My guess is the sprayer gets things loose but a back flush is still needed to get the tank clean.
azjeffh
Explorer
Jan 07, 2016
Adam H wrote:
Every one I have seen are funneled to the drain pipe, makes a big difference with how the flushers work.

Adam

I believe it makes a larger difference in how well the tank drains rather than the flusher's effectiveness.

I don't see how the results would be any different using the Sewer Solution or RV Hydroflush on a actual tank since neither added water to the tank during the rinse cycle.

In the tests of the Flush King and Tornado, I believe more would have been removed from the bottom of the tank during the rinse cycle. I don't believe it would change the result of the side residue left with the Flush King.

I'm not surprised with the results using the Tornado as spraying a tank logically should be the most effective. I was surprised however of the ineffectiveness of the Sewer Solution as it seems to have a strong following on this forum.

I have been using the Flush King for the last 11 years and do so because I have a sealed underbelly and installing something like the Tornado would just be too labor intensive for the benefit received.

I would suggest to the OP purchasing a water meter to monitor the gallons being added to the tank during rinse. I have found my Flush King adds 30 gallons between 3 and 4 minutes depending on water pressure. Also be EXTREMELY careful not to overfill the tank as you can have water running from your vent pipe, or even worse a ruptured tank (as some have reported). I have plenty of experience of doing what I’ve warned you about, and fortunately I’ve never ruptured a tank :)
Adam_H
Explorer
Jan 07, 2016
The only issue I saw with these videos is I have never seen an black tank with the drain out of the side. Every one I have seen are funneled to the drain pipe, makes a big difference with how the flushers work.

Adam
TrailerTravele1
Explorer
Jan 06, 2016
This video comparing tank flushers, including the Flush King, and using a simulated clear tank, was eye opening for us ... Very much worth the 25 minutes it took to watch. RVNet doesn't allow embedded videos, so you have to click the link below the photo, sorry.

https://youtu.be/dfTd0Slt_cU
2112
Explorer II
Jan 02, 2016
I have one of these twist on valves. I use it to not only back flush the black tank as described above but also use it to transfer some water from the gray to black tank.

We fill up the gray much sooner than the black and moving some of that water from gray to black not only allows us more time between dumps but also makes it easy to have a full black tank when it is time to dump. Furthermore, the drain pipe between the valves and twist on valve adds about 10 gallons of holding capacity.

I do not travel with this valve attached though. I'm concerned with is coming off while cruising down the highway.
stripit
Explorer
Jan 02, 2016
I used to flush the gray tank at least once per month, you'd be surprised what you can flush out of there. The soap residue is sometimes think and it flakes out when back flushed.
Bipeflier
Explorer
Jan 01, 2016
jplante4 wrote:
You don't need the extra flush king valve to accomplish this. Simply hold the stinky slinky up higher than the level in the tanks and open both valves. Let the gray water run into the black water for a few seconds (if you have a clear section you can see when it stops), close the gray valve and drop the hose.

If you use the "lift the hose" method, just make sure you have a really good sewer hose that the ends are firmly attached! The hose full of water gets heavy quickly and you don't want the connected end pulling off. Watch Robin Williams in "RV" movie to see what the results could be.

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