Holding tank monitoring options?

[bletso]

Yet another vote for the Tank Tender.

[peghall]

SCAD system - very difficult to install in the restricted space, and will only monitor the top few inches of the tank, so not much better than a "3/4 full" warning.

I suspect that it won't be easy to install any system. The SCAD/Profile system just has to be calibrated for the tank it's installed on. As long as the sender is placed where it needs to be (on a vertical wall at deepest end of the tank), it will monitor the entire tank contents once that's done.

[Kelkara]

Originally Posted by peghall

I suspect that it won't be easy to install any system. The SCAD/Profile system just has to be calibrated for the tank it's installed on. As long as the sender is placed where it needs to be (on a vertical wall at deepest end of the tank), it will monitor the entire tank contents once that's done.

That is a big part of the problem ... the deep end of the tank is not accessible without cutting away a lot of fiberglass.

[wsmurdoch]

Originally Posted by Kelkara

Tank Tender - simple and reliable, but still requires a small fitting in the V-berth, but that can probably be protected ... also very expensive. Home-made alternative? am I that brave when it comes to playing with sewage?

If you are game to putting a dip tube into the top of the tank reaching almost to the bottom for a Tank Tender, perhaps before you bought the Tank Tender, you could...

Buy a blood pressure cuff with a rubber squeeze bulb and gauge (aneroid sphygmomanometer). Cut off and discard the cuff itself. Connect the rubber hose that previously went to the cuff to the dip tube. Pump the bulb until the pressure stabilizes as air bubbles out the bottom of the dip tube. Read the gauge pressure in mmHg and convert it to inches of water remembering that 1 mmHg is about a half an inch of water. And, if the dip tube plugs, you can always go up to 300 mmHg (about 5 psi) to blow the s__t out.

https://www.amazon.com/MDF-Calibra-A...9&sr=1-16&th=1

[peghall]

So cut it! Sooner or later you'll have to replace the hoses--they may even be way past due already, 'cuz 10 years is the average working life of any hose...You'll need that access to do it.

[Ding Duck]

This should do the trick as well. You can use a Capacitive Prox sensor mounted on the outside of the tank. This particular one has a M18 thread, so if you can glue a M18 plastic (non Metallic) socket to the outside and screw this in. It will 'see' through the fiberglass and as the liquid rises, will change the capacitance and then switch. (this example is Normally Closed but should be able to get a N/O ). Just mount it at the 'high level' you require. Will sense up to 10mm
Connect +ve and -ve to 12Vdc and the 3rd wire to a LED Indicator etc. At $10 each, can't go too far wrong?
This style of sensor is also used in a lot of Industrial applictions where you need Non Contact due to nature of product being sensed.

https://www.amazon.com/dp/B00MCEK8PE?psc=1

[Dockhead]

Originally Posted by Ding Duck

This should do the trick as well. You can use a Capacitive Prox sensor mounted on the outside of the tank. This particular one has a M18 thread, so if you can glue a M18 plastic (non Metallic) socket to the outside and screw this in. It will 'see' through the fiberglass and as the liquid rises, will change the capacitance and then switch. (this example is Normally Closed but should be able to get a N/O ). Just mount it at the 'high level' you require. Will sense up to 10mm
Connect +ve and -ve to 12Vdc and the 3rd wire to a LED Indicator etc. At $10 each, can't go too far wrong?
This style of sensor is also used in a lot of Industrial applictions where you need Non Contact due to nature of product being sensed.

https://www.amazon.com/dp/B00MCEK8PE?psc=1

Check the thickness of your tanks before splashing out on these. Mine are 10mm (Tek Tanks). The maximum detection distance of 10mm of these is for an ideal material -- grounded metal. Detecting water will only work at less distance than that.

[LeaseOnLife]

Originally Posted by Dockhead

Tank Tender works great with black water tanks. NO FLUID needs to be inside the tube -- it doesn't work the way you describe. The pressure is sensed in the AIR when the pump is activated, not fluid. It automatically cleans itself.

OK, got it, no fluid in the tube while pumping and reading the gauge. Looking around Hart Systems - Home there seem to be pther ways to clog the tube in waste tanks:

Occasionally, after filling a tank the additional head from the fill pipe will force a little liquid up into the "bubble tube" causing an unusually high reading. Should this be the case, pump very slowly to force the fluid out of the "bubble tube" and thus obtain an accurate reading.

For waste tanks the manufacturer recommends a purge valve:

OPTIONAL: Purge Valve operation for holding (waste) tank -Flip toggle to "purge" prior to reading a holding tank; air will bypass gauge and purge TPF tube, if clogged; then flip back to "read" release valve button, repress and pump again for tank level reading. Do not pump beyond gauge capacity.

Since the user reports are all positive on tank-tenders with waste tanks, I plan on expanding my tank tender to also read waste tanks.

A multi position selector valve should do? This looks promising, 6 positions with 10-32 UNF thread for 1/8" tubing adapters:
https://www.pneumadyne.com/position-...dyaWQiO2k6MDt9

Dirk

[captstu]

Peggy, You posted above several positive comments about the SCAD/Profile tank monitor.

I've had extensive correspondence with Dennis - shipped my back to be tested, no problem found even though the switch tested defective when Dennis returned the unit to me.

I finally got tired of the hole in my head (truly, not a metaphor) and contacted Dennis who sold me a new one. Like the original, it worked a few times - not it works intermittently and sometimes just blinks without working. Contacted Dennis who explained the new one wasn't under warranty (I paid about $100 for just the readout end). Now I'm nearly $300 into the SCAD and he said the one I shipped back the second time was busted - and he would not warranty that one either.

He offered to ship me a third one (actually 4th counting returns), for the discounted price of about $42.

I guess I will just use the holding tank until it fills - or (as I do now), estimate the usage and periodically pump it out.

I suggest you recommend this device only with the caution that it is very sensitive to humidity - I've had two of the switches fail according to my ohm meter - and that it should not be installed on a boat - or at least not in the head compartment.

The device has no sealing at all - the circuit board and three push button switches are open to the humidity and are not a protected metal.

It may work for you - but for the majority of us who locate their heads on their boat, there is no chance.

Dennis is truly a nice person to deal with. He is polite, reasonable about the problem, but doesn't have a workable product and the warranty is only for devices that do not fail.

[peghall]

First story like yours I've ever heard. I definitely want to talk to Dennis about it.

[Kim Gregory]

Most holding tanks have the 1.5 inch pump out hose reaching to the bottom of the tank.
As the tank fills, each inch of this hose holds 1.76 cubic inches of water.
1 cubic foot of water weighs 62 lbs, so this 1 inch of water weighs 0.063 lbs.
To push that 1 inch of water down the hose, you need 0.036 lb / sq inch air pressure. ( 0.063 lbs / 1.76 square inches, the surface area if the hose ).
To push the water down a foot, you need 0.43 lb / sq inch (0.036 x 12 ) of air pressure.

( picture putting a styrofoam plug in the hose, and weighing it down with 3/4 lb of ball bearings )

Adapt a spare screw cap for your deck fitting, and add a low pressure gauge, and a tire valve. Pump air into the tightly sealed cap ( bicycle pump), and the air will push the water down the hose. When the air pressure is high enough, all the water is pushed out of the hose.

Read the air pressure gauge. If your tank is 24 inches deep, and the gauge says 0.8 lbs, then your tank is full.

Can anyone verify my math on this?
- Kim

[Dave22q]

I do wish the monitor was sealed but it is what it is. If I was really bothered i would seal it with one of many commercial products. Early on I had some issues and Dennis solved them. True, sometimes you need to reset the full and empty readouts but it's easy. Over 18 months in place and I'm still a satisfied customer.
Anybody can cry 'enough' if a customer keeps whining and that may be what happened here.

[Bill O]

We have an aluminum holding tank (yes, it's not ideal) and we purchased the Solo System from Dennis (SCAD type w/PVC tube insert made for metal tanks). We are on the third probe and for whatever reason they just stop working. Dennis has been nice enough to test and replace them for free, but unfortunately the product doesn't work for us. Dennis is a nice guy and I hate to keep sending them back, and since he can't figure out what's going on, we'll try something else.

Several years ago we replaced our fuel and water senders with WEMA senders/gauges and have had no problems/been very happy with them. So whenever they have a sale, we'll be switching out.

Bill O.

[peghall]

There are discussions about several tank monitoring systems in this thread...I think you've dropped information about the Tank Tender into the middle of some discussion about the Profile/SCAD system.

[Dockhead]

Originally Posted by Bill O

We have an aluminum holding tank (yes, it's not ideal) and we purchased the Solo System from Dennis (SCAD type w/PVC tube insert made for metal tanks). We are on the third probe and for whatever reason they just stop working. Dennis has been nice enough to test and replace them for free, but unfortunately the product doesn't work for us. Dennis is a nice guy and I hate to keep sending them back, and since he can't figure out what's going on, we'll try something else.

Several years ago we replaced our fuel and water senders with WEMA senders/gauges and have had no problems/been very happy with them. So whenever they have a sale, we'll be switching out.

Bill O.

My boat was delivered new in 2001 with WEMA sensors and gauges. Fuel still working fine. Water replaced one sensor six years ago. Black water second sensor failed a couple of years ago, when I switched to Maretron ultrasonic.

I would rate WEMA as "OK, but not great." The premium solution is Tank Tender, IMHO. Maretron - can't say yet how good it is, but so far no problems.