Gray water tank sensor/float switch

[Loiterer330]

I am have a constant problem with gray water holding tank on 2007 56’ Voyager. The electronic float sensor has been replaced several times in past 3 years. My mechanic suggested I use some bleach to help with soap scumb build-up. Any other folks had this problem, I wonder if wiring has been affected by moisture?

[Viper]

Wiring can certainly be the cause as well but if a new sensor has always solved the problem, it could be the root cause. The problem with bleach is that it's pretty harsh and too much of it can cause failures too. The type of detergents you use may also be contributing to the problem.

Do you know what brand/type of sensor it is? Maybe the answer is going with a different type of sensor/sender and monitoring system that won't be affected by the tank's contents. If it's a plastic tank, you can install external sensors that stick to the outside tank wall and won't be affected by sludge. There are also sensors that shoot ultrasonic/sounds waves from the top of the tank to determine levels such as Maretron's TLM1000. There is no probe sticking into the tank, just the transducer mounted on top of it. It's a NMEA 2000 system so you'd have to either have a network already set up as part of your navigation display/gear or set up a dedicated network and small display for monitoring tank levels. With a NMEA 2000 network, you can add more sensors for other tanks and systems, the possibilities there are endless. BEP makes an ultrasonic unit too (TS1) that has a resistive output compatible with just about any gauge/monitor.

[Coldcruisin]

Are you using the traditional white plastic float switch? They are notoriously unreliable. I just did this job this past weekend. I replaced the switch with an ultra bilge pump switch. I replaced 3 switches on my last boat and they all worked as advertised. Definitely worth a look.

[Viper]

Unless I misread it, I think he's talking about the sensor in his grey water tank, not the bilge pump float switch.

[Coldcruisin]

Hmmm... I wasnt aware of a level sensor in the grey water tank. At least not on my 45. Ill be interested to hear more.

[Viper]

You could be right, he may just mean the float switch. It'll depend on whether it's actually the grey water or black water tank.

[Viper]

Coldcruisin, after reading a little more carefully, you're right, it must indeed be the grey water sump. A couple of things in my first post still apply; the type of soap can sometimes make a difference and be careful with how much bleach is used. Bleach attacks the the shaft in the bilge pumps used in sumps. Instead of replacing floats switches, you'll be replacing a more expensive pump. You can probably delay the inevitable by cleaning the sump periodically, use lest soap, and if the galley sink drains into the sump, minimize the amount of grease going down the drain. As for the float switch, I think no matter which switch you use, cleaning it periodically is the key to proper operation, and as mentioned before, do check the wiring to ensure you don't have a poor connection or corrosion causing intermittent problems.

[Coldcruisin]

Good stuff Viper

[Viper]

...seal..., what I meant to say was that bleach attacks the shaft seal in the pump...

[Loiterer330]

Thank you Viper and all other folks that commented. My mechanic replaced a section of wire and connector, and once again the GRAY water pump is functioning. It definitely is GRAY water,and everything except the heads drain into this tank. Even the A/C condensation drains in. Thanks again to all.