Gray/black tank gauge issues?

Throw some tide liquid down the toilet (maybe 1/2 a cup) or Happy Campers Extreme Cleaner:
Extreme Cleaner
Just follow the instructions to a T and you'll get your clean sensors, the other thing is by letting your black tank sprayer go for about 10 minutes when you're rinsing. Keep your eyes on it, monitor it but 7-10 minutes this seems to clean off all the gunk on the sides of the tanks - at least for me it has!

The "button" type tank sensors the RV manufacturers use are flippin' hopeless yet they continue to install them. TP + p**p gets coated on the tank walls and stays there and short circuits the sensors. Flushing may or may not clean the tank walls enough and depends somewhat on the shape of a tank (3rd pic for ex.) and where the flushing device is located (in-tank, back flush elbow or in-tank wand). There are many different tank configurations and different outlet pipe locations and owners experiences can vary. Even if a flusher can reach the sensors, the force from the spray is likely insufficient to clean the tank walls enough. Some owners have found that the sensors have been installed at incorrect elevations, causing incorrect readings.

Horst Miracle probes (2nd pic) may or may not help and depends on the tank's shape and if they can get flushed well enough. We installed them on a previous TT and they worked great. Installed them in our current TT and they don't work at all. You can see how gunk could get trapped inside the plastic tube and would be difficult to flush clean.

Our owners manual says to use Liquid Drano to clean the tanks (doesn't attack metal or plastic). Works great to clean the tank back to factory new condition, however it doesn't take very long before the false readings return. Some use other methods & products to clean their tanks, but will still end up with false readings. We have a built-in flusher and it cleans the tank bottom below the toilet but not the probes.

I installed a shutoff valve behind the toilet and can peer into the tank to see how full it is. However, tanks are quite shallow compared to width and length and solids drop drop into the tank and build up below the toilet and you can't see what the rest of the tank is doing (solids don't soften and flow sideways in the tank). I find the "peer down the toilet" method using a flashlight works good enough.

The problem with a Seelevel setup, Horst Miracle probes or checking existing sensor elev. is that if you have an enclosed underbelly, removing and re-installing it is a major job.

Most simply learn to figure out fast a black tank fills up without using the sensors or looking into the tank. We've been able to get up to about 6-7 days for two of us. Putting in 3-5 gallons before using the tank and not scrimping on water when flushing helps quite a bit to make it last longer.

I’ve found that using the black tank flush works well and the monitor is accurate enough for both tanks. We try not to put any solids in the gray to screw up the sensors.
When leaving a campground, I empty, flush, add a couple gallons of water with Dawn and a capful of laundry softener. Has worked well for the 2 years we’ve had the Dart.

Mine work pretty well, one thing I've noticed is that you can't check readings right after using the tank. Water sloshes around and wets the sensors leading to bad readings. An hour later, tank readings are good.

I wanted to go with sealevel but my gray tank is too shallow as I recall correctly they require 5 or 6 inches of flat vertical minimum... my gray is just about 4".

I flush tanks thoroughly when possible, that might help.

you'll know when the grey water tank is full when it backs up into the shower or tub. Lost count of how many TT's I've had since the '80's, none of them, new or used ever had a gage that worked good. Become one with your black tank and keep an eye on the shower.

It's been my observation that those gauges are a much better indicator of how clean the tank is than they are of how full it is. After a camping trip, we always go berserk cleaning out the holding tanks, with multiple flushes and all, and they are accurately indicating empty. After we start filling them again, they go nuts. And the black tank indicator is worse than the gray tank indicator.

Flush those babies thoroughly, and next time you go camping, note how long it takes before they register full. After that, go by time, not by the gauges. They all lie unless the tank is spotless.

The design of the tanks are broad and shallow, this makes the sensors in the gray and black tanks easily bridged by scum, toilet paper and other debris.

There are various flushing devices, and techniques folks use to clean these but they are for the most part short lived.

Most folks learn to live with the gauges. The black tank is easy, as you can see it down the toilet. In our TT, once the gray tank fills the sink over flows into the bathtub.

It doesn't take long to learn to judge the gauge vs. tank level of your TT.

For most of us knowing how full the black tank is as easy as flushing the toilet and looking down while doing so, if you happen to not have a straight drop from toilet to tank this method is obviously not too effective. Best to leave exhaust fan off.

In over the decade of heavy use we never had the gray tank read anything other than empty after being dumped, nothing magical we just don't throw any food or other debris down the drains, just soapy and/or rinse water.

There are sensor cleaners for both gray and black tanks available at most RV supply stores, Walmart, and of course good ole Camping World. Some have developed their own concoctions for aiding with sensor accuracy.

We keep it simple and just use lots of water when using commode, we make sure tank is full (add water if needed) before dumping. We have a black tank flush which doesn't help much, but a quick rinse with tank wand and sensors work as intended.

SidecarFlip wrote:
Like I said a ways back, for me, looking down the pooper is the easiest and most foolproof way. It's a straight shot anyway so what it is, is. If the pooper tank is getting up there, the grey tank is too. You really cannot overflow the pooper tank because when it's REALLY full, the commode won't flush anymore.

Well, you're right. Low tech, but foolproof. Hard to argue with .

Like I said a ways back, for me, looking down the pooper is the easiest and most foolproof way. It's a straight shot anyway so what it is, is. If the pooper tank is getting up there, the grey tank is too. You really cannot overflow the pooper tank because when it's REALLY full, the commode won't flush anymore.