Black Water Tank Level Indication

[Andrew G]

The question: Do any of you have experience with the brands Raritan, Wema, Scad Solo, Tek Tanks and Gobius and any recommendations, comments or warnings regarding black water tank level indication?
Background: I have a “plastic” black water tank, approx. 70 litres, with an inspection port in the top but limited room, say 40mm, above that for fittings. The inlet and breather connections are at the top of the tank and the outlet in the very bottom of one side. It is of an irregular, but straight-sided shape to fit the hull.
I have little or no warning that the tank is full and I am looking to install some sort of sender and gauge. At the very least I need to know when it is nearly full. A gauge might be useful if not too expensive.
I’d prefer to not put holes in the tank but I can in the inspection port as long as the device will fit the available clearance. I’d rather not have devices that have to be removed for cleaning as it is a serious effort to access even the inspection port – but it can be done.
Any assistance would be appreciated.
Thanks, Andrew G

[sailvayu]

I know wema makes a unit that has a water flush fitting so you can clean it without removing but not sure you have the overhead room to install. I have a sealand float type in mine just the full indicator and have yet needed to clean it. I have not had much luck with the ultrasonic or exterior type but maybe some have more experience with those then I have.

[ranger58sb]

We have a WEMA system. Their new sensors are stainless, replacing the earlier plastic, and so far seem to be much more reliable. There's a moving float on the dip tube, and that changes resistance as it moves higher -- which is sent to the gauge for reading. The float can still stick, although that's often fixable by boat movement, and flushing the holding tank.

The system is adequate. If you install, you'll want to purposely fill the holding tank and read the gauge so you know what "ground truth" looks like.

There are some systems that don't require insertion of the sensor into the holding tank, perhaps useful if you don't have (or can't make) overhead clearance.

-Chris

[Calypso52]

We have a SCAD Solo in use for four years with no problems on the outside of a Ronco tank. I would never put a sender inside a tank if it could be avoided.

[Cormorant]

I installed a horizontal float switch in mine -- a hinged cylinder maybe 6" long, and when the outer hinged end floats up, magnets in the two halves will complete a circuit and let me light up my little warning light. . . . It worked once. . . . Then I believe some toilet paper or crap or something gummed up the hinge mechanism. I have an inspection port up top but I'm in no mood to go in and inspect. . . .

[Capn Morgan]

Replaced ours recently with the Wema mentioned above by Ranger. They seem to work fine but require space from the top for the installation process. Make sure you use good quality connectors for the wire to the gauge, and that you seal them properly with glue lined shrink tubing as they live in nasty places... On the top, I had to use sika to stop a minor leak as the surfaces were not perfectly flat.

[rtbates]

same problem. first indication of level was when the head pump had too much pressure...

Installed a monitor that has three tubes with floats that activate magnetic switches and different levels. It replaces the standard 4" inspection port. So far so good after three years.. SEALAND Tank Gauge at West Marine

[Capt.Don]

I installed the single-tank profile monitor from ferriellosales. These are the same as the SCAD unit and work very well. Aluminum foils are mounted outside plastic tank. You'll need about foot across for the two strips. The monitor has settings for different shaped tanks. I found the readings at 1/4, 1/2, 3/4 and full to be very accurate. Also has a red-light when the tank reaches 80% full. Be sure to order the holding tank montor with the tank-full option.
Don

[Andrew G]

Thanks for the comments so far (Wema winning but I would have to virtually pull the tank out).
Has anyone tried the Gobius, or similar?
(They stick 3 small pucks on the outside of the tank which "tap" it. Accelerometers in each puck measure the response to the tapping and conclude whether the fluid is above or below that point). Gives indication at > 1/4, 1/2 and 3/4 full. Less intrusive if it works and nothin in the tank. Andrew

[SV_Inspirare]

I'm using the Sensa Tank product to monitor my two holding tanks.
Extremely happy with the installation and use.

Installing them system consisted of two steps. Connect the panel to 12V and stick the sensors to the tanks.
The system only uses power when I press a button on the panel.

http://www.yachtproductsintl.com/pro...ctid=YPI-TS100
I think West Marine carries them too but this is a link to the manufacturer.

[SV_Inspirare]

I forgot to say that the reasons I picked this system were:
1. It was recommended to me by a friend.
2. I didn't have to open (or even touch) the holding tanks.

[Andrew G]

Inspirare - thank you. They certainly seem to "look the part" and do not involve ripping my tank out (and all the plumbing attached to it). Anyone else have experience with through the tank sensors - especially Sensa or Gobius? Andrew.

[LJH]

Originally Posted by Andrew G

Inspirare - thank you. They certainly seem to "look the part" and do not involve ripping my tank out (and all the plumbing attached to it). Anyone else have experience with through the tank sensors - especially Sensa or Gobius? Andrew.

I have the Gobius with one sensor puck set at about 3/4. I find it works well. The company gave good support when I had difficulty (my mistake) installing it. The only complaint we have is the brightness of the lights at night.

[Andrew G]

Thanks LGH, Andrew.

[ranger58sb]

Originally Posted by Andrew G

Thanks for the comments so far (Wema winning but I would have to virtually pull the tank out).
Has anyone tried the Gobius, or similar?
(They stick 3 small pucks on the outside of the tank which "tap" it. Accelerometers in each puck measure the response to the tapping and conclude whether the fluid is above or below that point). Gives indication at > 1/4, 1/2 and 3/4 full. Less intrusive if it works and nothin in the tank. Andrew

Don't consider my comments about our WEMA unit as a recommendation. It works well enough, but we have it because that's what came with the boat. And their customer service works well enough. Haven't investigated others...

-Chris