Black water tank sensor recommendation

[peghall]

Originally Posted by JBP

Alas, the capacitive sensors will not work on my stainless tank. The TankTender is crazy expensive, I've seen a similar one for RV black water tanks that is a lot less. https://horstmiraclegauge.com/

SCAD and most other capacitor tank monitor mfrs have a solution for that: they put the sensor inside a sealed PVC tube that goes into the tank. Unlike most systems with internal sensors, the sensor in the tube never comes in contact with the tank contents.

Most systems that use external sensors work on thick fiberglass tanks.

I'm a big fan of the SCAD system...unlike most, it doesn't provide just a 1/4, 1/2, 3/4 reading...you get a continuous level starting with just a few inches as the contents rise in the tank. And only ONE sensor is needed.

-Peggie

[goboatingnow]

Originally Posted by peghall

SCAD and most other capacitor tank monitor mfrs have a solution for that: they put the sensor inside a sealed PVC tube that goes into the tank. Unlike most systems with internal sensors, the sensor in the tube never comes in contact with the tank contents.

Most systems that use external sensors work on thick fiberglass tanks.

I'm a big fan of the SCAD system...unlike most, it doesn't provide just a 1/4, 1/2, 3/4 reading...you get a continuous level starting with just a few inches as the contents rise in the tank. And only ONE sensor is needed.

-Peggie

Trouble is SCAD is expensive you can’t beat $5 a sensor

[silvercreek]

Peggy, do you (or anyone else) know what signal the SCAD sensor is outputting?

I would buy that sensor as it does seem ideal, but would like to integrate it with the existing tank monitoring system I’m using for water, fuel, etc. The system can work with any voltage- or resistance-based sensors, but SCAD doesn’t seem to say what their output is.

[goboatingnow]

Originally Posted by silvercreek

Peggy, do you (or anyone else) know what signal the SCAD sensor is outputting?

I would buy that sensor as it does seem ideal, but would like to integrate it with the existing tank monitoring system I’m using for water, fuel, etc. The system can work with any voltage- or resistance-based sensors, but SCAD doesn’t seem to say what their output is (they want you to buy their monitor too).

Scad emulates both European and US ohmic range gauges. So it should just connect to an existing analog gauge

[silvercreek]

Originally Posted by goboatingnow

Scad emulates both European and US ohmic range gauges. So it should just connect to an existing analog gauge

Perfect.

I also found this after I posted, which shows some more details about how it works. I’m going to buy a couple and give it a try.

https://www.scadtech.com/TMHelp#sensor_output

Thanks all!

[peghall]

Give 'em a call on Monday and ask 'em.


--Peggie

[JBP]

Originally Posted by peghall

SCAD and most other capacitor tank monitor mfrs have a solution for that: they put the sensor inside a sealed PVC tube that goes into the tank.

Nice. That would work for my black water tank.

[goboatingnow]

Originally Posted by JBP

Nice. That would work for my black water tank.

As will any capactive sensor on the outside of a plastic tank and has the advantage of being impossible to block with debris.

[bobgarrett]

I tried those Chinese sensors but never got them to work reliably. This was on a plastic tank. I thought it might the minor variation in voltage so added a voltage regulator. That didn't work. Then I tried wiring each separately thinking they might interfere with each other. After two years of trying various solutions I disconnected them all.
I would love to know how others got them to work!

[goboatingnow]

Originally Posted by bobgarrett

I tried those Chinese sensors but never got them to work reliably. This was on a plastic tank. I thought it might the minor variation in voltage so added a voltage regulator. That didn't work. Then I tried wiring each separately thinking they might interfere with each other. After two years of trying various solutions I disconnected them all.

I would love to know how others got them to work!

I had no issue. Used Gorilla glue or Sika flex


Thanks I

[Colonel Bob]

Ditto on SCAD Tank Monitors. The new model from SCAD is more attractive and easier to read.

[Tudorsailor]

Originally Posted by bobgarrett

I tried those Chinese sensors but never got them to work reliably. This was on a plastic tank. I thought it might the minor variation in voltage so added a voltage regulator. That didn't work. Then I tried wiring each separately thinking they might interfere with each other. After two years of trying various solutions I disconnected them all.
I would love to know how others got them to work!

I had problems with calibration. However I cleaned out the tank this season and was surprised when the sensor lit up when I filled the tank with water from the hose. Dugh! I had calibrated previously using fresh water in the tank and of course the sensor did not work when filled with sea water + stuff. I recalibrated with sea water in the tank and now the sensor lights up as it should.

FWIW I also wired external LED lights and a buzzer.

TS

[Trawlerman]

FWIW, I have the SCAD monitor on my black water tank, and frankly it does not work in a useful fashion. I am sure it would work fine on fresh water tanks, but the calibration varies so horrendously dependent on the contents of the tank. It does seem to work on a quasi capacitive basis, but depending on the type of black water treatment chemicals used, the ratio of human waste to water, the ratio of #1 to #2, and so on. Virtually every recommend I have seen from Peggy has been spot on, but this is not a product that I would promote. It would not work on the exterior of my fiberglass tank (Marine Trader boat), due to the tank being too thick walled (turns out they glass encapsulated a wooden box), so on their recommend I bought a second sensor that is a PVC pipe with the electrodes inside. These two electrodes sealed inside the PVC pipe sense the level in a capacitive method. The variability of the readings drove me crazy, so I pulled the sensor and tried calibrating it in a 5 gallon bucket of water. This worked just fine, and was repeatable, BUT, once back in the holding tank, apparently the conductivity of the "liquid" in the tank has a very large effect on the accuracy, to the degree that the unit is essentially useless to me. I have seen one other poster who apparently has one and he quite properly challenged anyone to come and calibrate his unit. I wish I had read his post first.

[Scubaseas]

I've had SCAD on two boats now. One installed over 20 years ago. Both still working just fine.

[Noahr]

I have/use SCAD on my boat with two water tanks and one holding tank. They work most of the time but occasionally have to be reset/calibrated for no apparent reason…