Gary filled you in on the tank sensors. Now to the Flush King.
I have a slightly different setup. I'm not down grading the Flush King it all depends on the approach you want to take on tank clean out. The Flush King allows you to back fill the black tank or gray tank for that matter. It allows you to fill the tank partly and then dump again. It helps fill,drain, fill drain, fill, drain to float out the paper or other by products... from the tank. It does help.
I have a RV Hydro Flush combined with internal tank sprayers. Here is the Hydro flush in action.
I cannot get the Valterra link to go right to the Hydro flush. Select Tank cleaning products. Shop on line for prices, they are sold at most any RV parts place, even Amazon.
RV Products & Accessories
That setup was on my prior T2499. I still use it on the T310SR we now have now. When this is used in conjunction with tank sprayers you get the best of both worlds.
With tank sprayers you slide your normal dump valve closed and let the internal spray run for 1 to 2 minutes then dump. This creates the same action as the Flush King for tank backwashing.
The Flush King, Flush King
also made by Valterra is the RV Hydroflush with a dump valve added to it. You close the extra dump valve and then open the water inlet to back fill the tank system.
The Flush King seems to have been upgraded over the older ones. The water inlet seems to be installed at an angle that can spray up the pipe into the camper. When I was looking they did not have that. However there are 2 pics of it, one is and one is not so if you go the Flush King route my thought is get the one that points the water hose up towards the camper verses down the waste hose. This way you can blast the pipe in the camper to help clean it better and flush the drain hose. The RV Hydro flush has this feature and it seems they now moved it into the Flush king.
OK by now I may have confused the issue, what's the difference?
There are at least 5 ways to do a black tank dump and flush. Others can add in even more....
1. The 5 gallon bucket
. This is the cheapest way do a dump flush. Fill it up, haul it in, push the pedal down and dump it in. It helps for sure but does not always get every corner of the tank or the sensors. All black tanks are not created equal and some are long and taper down hill with the toilet hole on the upstream end. These flush out easier then other setups with more flat tanks or where the outlet and toilet as close to each other.
2. The wand.
This method is the best for getting just about everything flushed out in the black tank. Wand and Johnny chock
or Wand only
Or The swivel stick complete with U tube how to instructions
There are more brands too.
The wand hands down you can get every area of your tank flushed out. We have the swivel stick and a separate Johnny Chock only. We use the Johnny Chock more to just transfer the rest of the fresh tank to the toilet at the end of the camping trip. It holds the valve open so you do not have to sit there for 3 to 4 minutes with the pedal down.
One heads up on any brand wand! Install a solid brass shut off with metal ball valve and handle on the end of the hose then screw the wand on. Do not rely on the wand plastic shut off or even and extra plastic hose shut off. Ask me how I know this
They sell the brass with metal valve stems ones at Lowes etc made to screw on a hose.
When we bought the T310SR early on I did not have the tank sprayers setup yet so we hauled the wand in. I even had a 2nd metal and plastic valve shut off on the hose. Hose up through the bath window, valve was off and then I went in and Cindy turned the water on. When I picked up the hose the plastic shut off valve stem blew off the back up shut off.
OMG... Water blew every where.... The poor roll of toilet paper took a direct hit and poof, all over. "Cindy, shut it off. Shut what off...." The wand valve never blew it was the back up valve....
After 5 seconds of total chaos I put my hand over the gusher trying to seal it off. Bam, it flew right up and drenched me
. By now I had the wand down in the toilet and the gusher directed into the bowl. Cindy finally shut the hose off outside.
That was 60 seconds that can sure kill a happy ending to a camp out...
Mopped up the mess and went home....
3. Internal Tank sprayers .
They make a few kinds. The ones that spin and the ones that don't. Quicke Flush - non spin
Or The Tornaodo
They make other brands of non spinning ones. I have had both. Here is the Tornado install.
Here is PTHutch's install
The sprayer of either type eliminates the wand for the normal campout flush deal. I still have the evil wand... LOL, but have not used it since the tank sprayers were installed. You install the sprayers at the far end of the tank to spray towards the outlet and get the tank sensors hit with spray at the same time. These allow a good coating spray of water over the inside of the tank without hauling the hose in the camper. And by closing the drain valve we can back flush the tank like the Flush King.
4. The RV Hydro Flush.
If your dump valve is straight in line with the tank outlet this can shoot right up into the tank. Valterra Hydroflush
This is the ideal setup with this unit as your get some spray action inside tank and the pipe on the way out along with the drain hose when used only by itself and no tank sprayers. If your tank has an elbow on the end of the tank the spray up into the tank is not very effective but helps blast the pipe area and the drain hose. With no tank sprayers you cannot back flush the tank as there is no shut off valve down stream of the water nozzle.
In my case I use this in combination with the tank sprayers to do a tank back wash and a hose wash out.
5. The Flush King.
There are now 2 brands of this concept
The Camco version with U tube video
The Flush King by Valterra
Heads up on the water spray. The new ones point to the tank, the older ones point to the valve.
If you do not have tank sprayers this allows you to close the valve and back flush the tank by pumping water in back up through the tank outlet valve. They work well just they do not direct water in a spraying pattern all over the inside of the tank. Also do not over fill the tank when back filling.
So what system is better? And what brand is the best?
They all have pro's and cons.
I have the RV Hydro Flush and internal tank sprayers. On the T310SR with flat tanks that are enclosed tanks this is high up on my list of have to haves to get the tank clean. The wand will work too but....
On my T2499 tapered long tank I also had the RV Hydro Flush and internal tank sprayers. Since I had 2 elbows at the end of the tank I could not shoot up into the tank with the Hydro flush. The system worked well for us.
If you not want to add tank sprayers, the newer Flush King or the Camco with the water nozzle pointed up to the tank will be a good option if you do not want to use the bucket or the wand.
I have found that regardless of what method you use, get the tanks clean and keep them clean after each dump. Staying ahead of the build up inside the tank before build up occurs is key.
The amount of dumping and flushing products to pick from is well, big. Fell free to use SOC as a RV'er consumers report and ask away who had what brand and do they like it.
Good luck and hope this helps
PS the cracking of the plastic on the Flush King. The RV Hyro flush has the same problem. Made by the same company and same plastic. I have had mine since 2003 and still using it. However I bought a new one this year as a spare. I will UV blocker treat the new one before using it and then once a year or so. 303 UV protectant. We normally do not use full hook up much exposed to the sun so I do not know if the sun is making them brittle or the chlorine in the water or both. Having the clear 45 degree elbow to see what is going on is worth the cost. And they do sell just clear elbows too. With out being able to see what is coming out, you have no idea if you got everything out or not.
PS2 With the tank sprayers you have to air blow them out for winterizing or pump antifreeze in the lines or they will crack over the winter