Holding Tank Sensors - RV-Dreams Community Forum

NorCal Dan · RV-Dreams Family Member

Holding Tank Sensors

LeslieW · RV-Dreams Family Member

We had the See-level gauges installed on our Hitchhiker. Check out http://www.rvgauge.com/rv.htm The gauges measure in 5% digital increments and are located on the outside of the tanks so they never foul.

NorCal Dan · RV-Dreams Family Member

I'm curious how those sensors work when they are on the outside of the tank. I've heard of ultrasonic sensors, is that what they use?

I try not to re-engineer things on my coach because I don't think I'm smarter than the guys who built it. I want to believe that my holding tank sensors should work and it's me who somehow messed things up.

I read about a device that people use to back flush the tanks called a King Flush, it attaches between the dump valve the stinky slinky hose. You hook a water hose to it and I guess it will fill the tank without letting the water drain out the stinky slinky. I have been thinking of getting one just to see if a second flush on the grey tank would make any difference.

I've talked to folks who tell me they don't use chemicals in their tanks and gauges read fine. I never looked but I guess the same chemicals used in black tanks could be used in gray tanks, but I'm skeptical that it would help with my problem.

Because we have a washer/dryer I am usually dumping the gray tank every 2 or 3 days. I don't leave my stinky slinky hooked up so the valves stay closed until I dump. I would have thought that dumping that often would prevent these problems.

LeslieW · RV-Dreams Family Member

I don't know how the See-Level works from an engineering perspective. Perhaps you can tell from their website. I know many people who have added it as an after-market improvement. Most people I've talked with complain that their internal tank sensors don't work well after awhile.

We have two separate 50 gallon tanks for gray water (galley and shower). Originally we did not put any chemical in the galley or gray (shower) tanks. After a few months, the galley tank seemed to drain slowly. We now do use the same chemical for the galley as we use for the black tank. Although we're very careful about trying to prevent grease and food scraps from getting into the galley tank, I understand that some food waste will enter the tank via dishwater. The chemical helps dissolve that waste. The instructions on the bottle of Cameo RV TST-Free Holding Tank chemical instruct 2 oz for the gray tank and 4 oz for the black tank.

NorCal Dan · RV-Dreams Family Member

I decided to try using the chemicals for the black tank in the gray. Will see what happens.

Also, I checked the website and they don't say how the sensors work...

Speedhitch · RV-Dreams Family Member

I am assuming you do not leave your grey water dump open?? You let it fill up and then dump it. Is this because you are boondocking? Just curious I never close my valve and we have never had that problem. I have probeless sensors. The grease from your kitchen can cause the sensors to foul. Then too you could have some faulty sensors which has nothing to do with the condition of the tank.

Joe and Sherri

dream reachers · RV-Dreams Family Member

NorCal Dan wrote:

I am having a tough time keeping my gray tank sensors reading correctly. The black tank has abuilt-in sprayer that I use each time I dump and the sensors are fine. But no such luck with the gray tank. I have used the level sensor cleaner a couple of times, and that works for about a month before the sensors misread again. I was thinking of asking the dealership if they could install a sprayer in the gray tank. So does anyone have ideas? I also tried the GEO method, but I think the sensors need to be really clean before starting this regime.

I saw this same problem brought up on the Escapees Forum recently under "tips and tricks" Someone had said they had great results with "Elemonate" that they purchased at Camper World. www.rvsanitation.com/elemonate.html
Good luck, this might be an easy fix.

blijil · RV-Dreams Family Member

It seems that the standard internal tank sensors are easily coated with a film present in most emulsion type cleaners and soaps. Different types of sensors including doppler, capacitance, floats, sight glass, and even weight have been reported in the forums however they all seem to problems. We kept track of how long and how much we are putting in until we got the hang of when we need to dump. Only the sensors on the fresh water tank seem to work reliably. We have cleaned out more than our share of sink traps over the years and have never found on that wasn't slimy with soap residues.

Good luck on working out your routine.
Larry and Jacki

thebearII · RV-Dreams Family Member

Every RV we've had, the sensors eventually stop being effective due to build up.

Like others in this forum and Escapees forum have said we just keep track of when it's time to dump.

If it's just the two of us, we know we can survive for 5 days boondocked before we run out of water or need to dump with some conservative water use. Or for 8 days if we are very careful (use paper plates, cook on the outdoor grill to save clean up...very short showers, turn off the ice maker...I use the camp area restrooms if available).

-- Edited by thebearII at 10:28, 2009-01-12

NorCal Dan · RV-Dreams Family Member

Some good information...thanks for the replies. We do not leave the gray valve open. I tried it once but had terrible fumes from the septic system.

Coach has a macerator so normally I am not hooked to the dump. So yes, tanks do not get dumped until they are full.

Before we added the washer/dryer I could go about 4 days before dumping the gray tank. Since we always have hookups we don't practice conservation. We don't waste water, but we don't go overboard trying to conserve water either. Black tank will last about 8 or 9 days before needing to be dumped. After we added the washer/dryer I have to dump the gray about every other day. The washer doesn't hold much so we usually do one load a day, sometimes 2. These new machines don't use a lot of water, just enough to get the clothes wet.

The elemonate sounds promising...thanks for that link. I will be giving it a try.

It sounds like this is a common problem...now I don't feel like an idiot for not doing something I was suppose to be doing :)

NorCal Dan · RV-Dreams Family Member

Went to the local RV shop here in Benson and they didn't have elemonate, but they did have a Thetford product in a big bottle. It didn't specifically mention cleaning the sensors.

Then I found small 4 oz. bottles named Pure Power waste digester and it does specifically mention sensor cleaning. I just drained the tank and then filled it with clean water and then added the 4 oz. bottle. Directions say to leave it for 12 hours. So will let it sit overnight and drain in the morning and see how it goes.

I did check Camping World and they carry Elemonate, it was about $10 for a box of tablets, and the shipping would have added $12, so I passed.

Will see how it goes with the Pure Power stuff as it was only $1.79 a bottle and I bought 2 in case I need to do this twice

-- Edited by NorCal Dan at 20:27, 2009-01-12

Speedhitch · RV-Dreams Family Member

Dan...you can try making a "P" trap in you slinky line and that plus the "P" traps in your RV should eliminate any sewer smell that you have. This way you could leave your grey tank open and not worry about the probes.

Speedy

NorCal Dan · RV-Dreams Family Member

Hi Joe, I thought about doing that...I need to get a sewer hose ladder and I will modify it to incorporate a p-trap and see if that works to keep out the smell.

FWIW, the chemicals I tried in the gray tank did not work. Well, it didn't help with the sensors. I suspect that the grime in the tank is heavy and it will take multiple attempts to get it cleaned out. So I will keep at it and see if I can get the tank cleaned. I am also looking at adding a galley hold tank to keep the cooking grease and food stuffs out of the gray tank. It could easily be hidden in the basement under the kitchen and have a separate drain. 10 gallons would be plenty as long as it was easy to dump. And the savings on a chemical regime for the gray tank would easily offset the cost of adding the tank. I could probably use one of the portable tanks I see for when camping without sewer hookups.

I will tackle this once we get to our summer workamping job.

-- Edited by NorCal Dan at 11:22, 2009-01-15

CampingGalore · RV-Dreams Community Member

We have also had trouble with the sensors in our tanks so we bought a Flush King and use it to flush both the grey and black water tanks (we also have a built in sprayer for the black). This has helped immensely to clean all the goup off the sensors. The Flush King has been well woth the money. It was actually Howard who wrote about it on RV-Dreams!
We have also heard that putting Calgon down the drain will help but I am not so sure about that. Good luck!
Susan & Pat Cronin
2006 Mobile Suites TK3

TXRVr · RV-Dreams Family Member

I don’t even use the sensor system anymore. It has never been that accurate and as everyone has validated, they get worse with time. If in one place for awhile, I dump gray water when it’s obvious to do so. That for me is when the shower water does not drain completely. When it happens, I am sure that the tank is full. But this subject makes me wonder. Is there a logical reason why one would dump before the tank is full (exception being smell)?

Norcal> My washer/dryer manual states that the dump valve should be open when doing laundry. But I suspect those instructions are for the lowest IQ user to keep from backing water into the RV if the tanks already had water in them.

I have external clean out flush valves, but I’ve found the most effect method is to put the chemical –what ever the preference may be- in a half full tank of clean water and then drive to my next campground. The sloshing back and forth works much better than spray action. Recently a fellow RVer said that he puts crushed ice in his black tank and does the same. As it melts, the ice (small junks) effectively clean the tank. Never tried it. Has anyone else?

NorCal Dan · RV-Dreams Family Member

All good advice. Yes, washer/dryer states to have the dump valve open, but I asked about that and was told it was to prevent overflowing the gray tank.

The only problem I have is with the gray tank. The black tank sensors work fine, as long as I allow the flush to get them clean every time I dump. But I am afraid the gray tank has been ignored too long and the build-up of kitchen waste has fouled the sensors.

My current plan is to soak the gray tank 2 or 3 times before we move, and then on moving day I will add a full dose of level gauge cleaner and some Calgon water conditioner. I am hoping the pre-soaking, then driving and sloshing, and the very soft water will get the sensors clean again. Unfortunately I can't add ice to the gray tank.

For a long term solution, I am not sure what will work for us. Chemicals seem to be the easiest path, assuming I can find something that will work. I am still hopeful that if I get the sensors cleaned the Geo method will work.

NorCal Dan · RV-Dreams Family Member

CampingGalore (Susan or Pat not sure) I looked at the Flush King. It doesn't appear to do anything other than fill the gray (or black tank) with water, it just does it backwards, ie. bottom to top. I don't think it would be able to spray the water into either of my tanks due to bends in the pvc pipe between the dump valve and the tank itself. If that is in fact all it does then I don't think it will help with my current problem. Backflushing the tank after each dump may be a good long term solution to keep this from happening again, but right now I need to get the sensors reading correctly.

Jack Mayer · RV-Dreams Family Member

The only effective way I've found to clean out the grey tank (get all the soap scum and grease out) is to first empty the grey tank, then put about half a cup or so of dishwashing detergent down the kitchen sink, then dump your ENTIRE hot water tank down it. Then drive to your next destination. Empty the tank when you arrive to keep everything from settling back down. Do this a couple of times and you will have a fairly clean tank.

NorCal Dan · RV-Dreams Family Member

That's a good idea. Dawn is suppose to break up grease. I will use this in the pre-soak I do before we move as well, couldn't hurt...

Tom-NC · RV-Dreams Community Member

Dan,
I would like to offer some advice if I may. Number one the flushing of the tank with Dawn and some water then traveling should work. Also when in a campground you should leave the grey tank valve open and if you are getting a stink in your coach it must be coming from the vent on the roof getting back into the coach from an open window or roof vent. The grey water system whether in your home or in your coach has "P" traps which are normally full of water to prevent smell from getting into RV.

Another point would be to ask what kind of laundry detergent is your wife using? We have a septic system here at home and we have to watch what kind of detergent we use. If she uses a powder detergent there is your problem. Number one when she adds the detergent to the wash and you use hot water everything works fine, however when you dump it into the tank which is cold or cooler the detergent hardens and becomes a big glob. Tell her to use liquid detergent and use All or some other liquid that is biodegradeable.

The macerator system is good but there must be a flow problem going into a smaller hose. Try the standard size hose when dumping the grey tank.

Lastly if all that doesn't work I would get a jumper wire and go between the common wire and each sensor location and see if gauge is working properly. Then remove sensor screws that are on your grey water tank and clean then and then reinstall them be sure to use silcon sealer before reinserting them.

Hope this is helpful but grey tanks very seldom give any problems. Oh one last point We don't allow and grease into the kitchen sink. If DW uses a fry pan she wipes it out with paper towel and then throws away the towel. Watch what you put down the drain.

Tom

bjoyce · RV-Dreams Family Member

A friend just put a built-in sprayer on his gray tank. The hardest part was getting to the tank but he did the work himself. That might help your sensors.
We have external sensors on our tanks and are very thankful they are fairly reliable.

NorCal Dan · RV-Dreams Family Member

Just a follow-up on this thread...after trying different options that didn't work...I was in Amarillo getting some work done on the coach...I bought a bottle of degreaser. I put it in the tank for 3 treatments while staying in Oklahoma City. The day before we left I dumped the gray and black tanks, then did one load of laundy. On the morning we left we both took showers. I then added another treatment to the gray tank and then headed for Branson. I waited 2 days to make sure the tank was full before dumping. I just dumped and my sensors are reading empty...hooray!

FWIW, the guy in Amarillo first recommended the Level gauge cleaner that I already have, and if used the same way probably would have worked. But because I thought the problem was grease he recommend the degreaser product. It's nice to have all the gauges working again...

gypsy97 · RV-Dreams Family Member

Since my black tank sensors aren't reading properly - show full after I dump the tank even though I can hear it emptying - I have been looking for previous posts on this subject. I always use a packet of deodorizer and plenty of water after emptying the tank, and also I've started using just a small bit of Calgon water softener to all the tanks each time. The rig has been sitting parked for nearly 3 months, and when I move it next week I'm going to use a couple bags of ice in hopes they clean whatever might need cleaning inside the black tank.

I have the connection for attaching a hose to flush the tank out, however, I've been afraid to use it because when I do I never hear water running back out from the tank. Where is it going? What can happen if somehow the connection is messed up?

gypsy

Luvglass · RV-Dreams Family Member

When you back flush the tank the water doesn't come out fast enough for you to hear it. The only way you can check is too pick up the exit end slightly out of the sewer fitting and you can then see it discharging. If your black tank valve is open I wouldn't worry about checking it, just run it for a few minutes, shut off the water and close the discharge valve. You'll be fine.

As for the sensor valves, they all stop reading accurately after awhile. after a while, you will develop a sense of when they are full depending on your usage. We hardly ever check ours, we just "know" when to dump.

Good luck,

desertnurse · RV-Dreams Family Member

Glad I searched for this topic, as it answered all of my questions (gypsy97-I actually checked the poster ID to make sure I hadn't sleep posted this!).

Good to know that there isn't anything "wrong" with the coach even though the blackwater gauge is misreading. One question-what does one do when trading in or reselling? I would feel a little oogie about buying a coach that always reads 3/4 to full on the black tank gauge....

As always, thanks all!!

NorCal Dan · RV-Dreams Family Member

Wow! An old thread. Now that we have been at this awhile I can share my experience.

The problem with sensors is they get covered with gunk and give the full indication when the tank is empty. I am happy to report that we don't have problems with our sensors and they read correctly all the time now.

What did I do to get them working correctly?

First, the most important thing is that you need to get them clean every time you dump. Since we now leave the gray valve open this really just applies to the black tank. Every time I dump I make sure I continue to flush the tank until the sensors show empty. I turn on the sprayer and pull the handle. Once the tank is empty I wait a couple minutes before closing the handle. This ensures that when I close the gate valve I won't trap solid material in the seal. I leave the sprayer running and I go inside and fill the toilet bowl full and flush about 4 times. I then go outside and pull the handle. I continue this cycle until the gauge reads empty.

We move once or twice a year going from one workamper job to the next. Before we break camp I do a flush of the tanks. I then fill both tanks to the half mark. I then pour half a bottle of Thetford Level Gauge Cleaner into each tank. We then hit the road. When we stop for the night I drain the tanks and flush again. I then do the same thing on day 2. This makes sure the tanks are very clean before we reach our next destination.

Using this routine keeps my gauges reading correctly year round.

The degreaser I bought in Amarillo was great stuff. You just put it in the tank and use the tank as normal. Unfortunately I didn't save the name of the stuff, wish I had because it worked great. But the Thetford stuff I use is ok as long as the outside air temperature is above 70 degrees. It works even better as the temperature goes above 80.

Early on we did have fume problems in the coach that I thought were caused by me leaving the gray valve open. What I think really happened was when I drained the tanks I wasn't doing a good flush. Since I changed my flush routine we have not smelled anything.

The tanks can be professionally cleaned. I suspect dealers do this on used coaches since the units tend to sit on the lot for a long time. Basically they use a power washer/sprayer inside the tank.

ahoweth · RV-Dreams Family Member

I have had this problem from time to time. I go to WalMart, buy a box of denture cleaner tablets, dissolve the entire box in a pitcher of water, this allows the fizzing to abate, then I pour it into the gray tank and fill it with water. I let it sit for 4 to 6 hours and then dump it. The gauges work perfectly after.

desertnurse · RV-Dreams Family Member

We actually have a power sprayer at our disposal...how would we do this?

NorCal Dan · RV-Dreams Family Member

Through the toilet is one way. Helps if your toilet is mounted directly over the black tank with turns in the pipe.

But I would try some good chemicals first. If your located in warmer weather (say above 75) I would try the enzyme based chemicals. Dump the tank. Flush the tank real good, if your tank doesn't have a built-in sprayer then run a hose through the window and fill/dump the tank a few times. Then fill it and add the chemicals and let it set for 2 or 3 days before dumping, just to give the chemicals a chance to work. If you can take the rig for a drive then fill the tank three quarters with water, add a couple bags of ice cubes via the toilet, then drive around for 30-60 minutes.

Or try some of the other ideas mentioned in this thread, ie. the denture cleaner tablets. Whatever method you try I would still recommend doing a very good flush of the tank before starting. I can do 3 or 4 flushes of my black tank before I stop seeing toilet paper coming out the drain. It's a good idea to have a clear connector at the dump valve so you can see whats coming out.

Here's some links to check out:

Example of flush through the toilet
http://www.campingworld.com/shopping/item/flexible-tank-wand/14497

Example of a clear adapter for your stinky slinky
http://www.campingworld.com/shopping/product/clear-sewer-adapters/3709

Add a blank tank sprayer
http://www.campingworld.com/shopping/item/no-fuss-flush/3495

BillA · RV-Dreams Family Member

I noticed a dealer offering an option of a flush/spray system for the gray water tank similar to what is installed in all black water tanks. I had never considered this but wondered if that is a option that should be considered if ordering a new rig. What are your thoughts?

53 Merc · RV-Dreams Family Member

On another forum, a member mentioned they had used ammonia to do some cleaning in the rig. Then quite a bit of ammonia got in the grey tank. He did not dump it right away, but when he did, he noticed some large chunks of material coming out (like me, he uses a clear 45 degree angle sewer connection). So, being of inquisitive mind, he put a bunch of ammonia down the grey tank. Filled with water and again saw a lot of chunks coming out. Also, the color was bad. After the second treatment, he was amazed that his indicators worked again after 3 years of not working. Could be a way to help.

One word of caution, NEVER add ammonia and bleach at the same time. Bad gas.

LeslieW · RV-Dreams Family Member

Before we installed SeeLevel our grey water tank sensors didn't work well. We tried Jack Mayer's idea of dumping some dishWASHER "Cascade" (not dishwashing) detergent in the galley tank, adding the entire hot water heater's worth of hot water and driving to the next destination. It worked like a charm. The advantage of Cascade is that it is designed to destroy grease and it does not make bubbles. Now we occasionally add TSP (available at Home Depot and paint stores) to the galley tanks to keep them clean.

NorCal Dan · RV-Dreams Family Member

BillA wrote:

I noticed a dealer offering an option of a flush/spray system for the gray water tank similar to what is installed in all black water tanks. I had never considered this but wondered if that is a option that should be considered if ordering a new rig. What are your thoughts?

I know camping world sells tanks sprayers that you can add to either tank. I thought about adding one to my gray tank. Personally I don't think the sprayers work that good. The one thing they do is add clean water to the tank(s). Flushing the tanks with clean water seems to accomplish more than just spraying. If I turn on my black tank sprayer and leave the drain valve open the sprayer will not "clean" my sensors. But if I leave the drain closed and allow clean water to fill the tank and then dump seems to work better for me.

So to answer your question...if the cost is minimal I think it would be nice to have a sprayer in the gray tank. If for no other reason than to be able to fill the tank with clean water to aid in cleaning.

bjoyce · RV-Dreams Family Member

Put a timer on with a loud alarm when you close the tank and run the internal sprayer. I have known multiple people who have gotten distracted and had floods.

Colorado_Kid · RV-Dreams Family Member

Fill each holding tank halfway with water and whatever cleaning chemical you use and drive around for 15 minutes allowing your cleaning chemical to splash around the tank cleaning the sensor. You could do the same thing with your fresh water tank adding baking soda to water.

Here is a device I have that at first I wasn't sure what it was for. I posted a photo in a thread I started here last Summer to see if anyone here knew what it was. It is used to clean holding tanks. To read the thread click http://rv-dreams.activeboard.com/forum.spark?aBID=91511&p=3&topicID=36551461.

CampCrzy · RV-Dreams Community Member

Hi, I'm new here and I realize this is an OLD thread but I wanted to share my experience.

My bathroom sink had a crack in it so for awhile, after cleaning my denture, I was dumping the solution down the commode.

By the way, I'm a full timer so my tanks get dumped weekly. Then I realized about ten days had passed since my last cleansing and what's this? NO odor.

Unheard of in my world.

Since then, my denture cleaner, which is naturally formulated to kill bacteria is the ONLY treatment my black tank gets.

Quite a bit less expensive than the enzymes and so far, much more effective and who doesn't love that minty freshness?

Racerguy · RV-Dreams Family Member

CampCrzy wrote:
Hi, I'm new here and I realize this is an OLD thread but I wanted to share my experience.
My bathroom sink had a crack in it so for awhile, after cleaning my denture, I was dumping the solution down the commode.
By the way, I'm a full timer so my tanks get dumped weekly. Then I realized about ten days had passed since my last cleansing and what's this? NO odor.
Unheard of in my world.
Since then, my denture cleaner, which is naturally formulated to kill bacteria is the ONLY treatment my black tank gets.
Quite a bit less expensive than the enzymes and so far, much more effective and who doesn't love that minty freshness?

This is a good reason for activating an old thread. We used generic denture cleaner pills and put them in all three tanks.Lo and behold our typically inaccurate tank monitor panel became pretty accurate again.

Lucky Mike · RV-Dreams Family Member

fill the tank and put a box of denture cleaner tablets in there......been there , done that....this process works real well and costs 3 bucks!!!!!!!.......(dont use your mates tablets , they tend to get upset!!)

Clay L · RV-Dreams Family Member

The problem is not the sensors being dirty but is due to the tank walls being gunked up and fooling the sensors.

Even the non-contact sensors on the outside of the tank can be fooled if the tank walls are cruddy enough. SeeLevel even points this out on their web site.

The SeeLevel web site says "If sludge buildup in the tank becomes extreme the gauge will cease to operate (the tank will always read empty), so by monitoring the signal level the tank can be cleaned before the buildup gets excessive".
From www.rvgauge.com/downloads/705_Owners_Manual.pdf">HERE

Anything you do to help keep the tank walls clean may help.
Flushing, adding some detergent and water before you drive for a day or so might help.

I have the TrueLevel non-contact system that Winnebago went standard with in 2005 and right now my black tank reads full when empty. The gray tanks shows 2/3 full when empty.

Over the ten years we have been full timing I have tried everything people say will work and nothing worked.
If I pressure wash the inside of the black tank (have done that twice), the level will be measured normally for a few months and then start to lie.

I think the problem is worse for full timers and that may be why some weekend or short term campers find that detergent or some other method works for them.

I just dump it every ten days and don't worry about it anymore.

In answer to a question above most non contact sensors either a couple of strips that have capacitive coupling or an stick on active sensor patch that also uses capacitive patches in the stick on sensor.
As the liquid rises the capacitance of the sensor changes and this is detected and processed by the level circuit to give a level display.

Regarding odor. Except for the roof vent it is a sealed system. If the odor is not coming from the roof vent then you have a problem that needs to be fixed.

You should have water in all of your traps and the toilet bowl. The air admittance valves under the sinks must be working properly.

I do use a venturi type vent top that sucks air out of the tanks while moving and if there is any breeze.