Determining Black water tank level

woodster · Aug 2, 2015

use the search on this site for tank level sensors the is one that mounts on the outside of the tank ...Peggy Hall ( the head mistress) has posted several times about this

seadaddler · Aug 2, 2015

Tank Guage

Look here or just look on internet under marine tank gauges and here yes many available and also have been told by other sailors about many different
types on the internet and the ones that mount on sides of tank are way better than sensors in tank getting clogged.
Nick

Apex · Aug 2, 2015

there was a similar topic last week, that Peggy also answered. Monitor that mounts to the outside of the tank. Check Peggy's profile for her posts and you will surely find all the sage advice you need. Good luck.

jsalley · Aug 2, 2015

I happen to have a nearly new Profile holding tank monitor sitting on the shelf, that I removed from my boat last fall to replace with a multi-channel monitor (it was the OEM install on my C355 - see photo). This is the monitor recommended by Peggie Hall and that received high marks from Practical Sailor. I'd be willing to part with it for a reasonable price - PM me if interested. You would need the tank sensor and foil strips, which are available from Sailors Solutions for $38, as well as other suppliers. This is an external mount, and works quite well.

Jackdaw · Aug 2, 2015

You're on a lake. Just pump out often!

I think Peggy figures 3 gallons/day/person. That works out for us. If we can, we pump out when we cross what we think is half a tank.

Electronic tank gauges are problematic, can have accuracy issues, and are one more gizmo to go wrong. Nice when you have to stretch the range of your tank, but for most weekenders they are overkill.

Peggie Hall HeadMistress · Aug 2, 2015

Electronic tank gauges are problematic, can have accuracy issues, and are one more gizmo to go wrong...

That may be true of gauges that use "probe" senders that are inside the tank 'cuz the animal fats in waste clog up the senders...but when installed according to directions (a novel concept, I realize) the top rated gauges which use senders attached to the outside of the tank have a VERY low failure rate because the sender never comes in contact with the tank contents.

...nice when you have to stretch the range of your tank, but for most weekenders they are overkill.

Not necessarily. USCG regs require that all waste holding tanks be equipped with a means of letting the owner/user know when the tank is 3/4 full. If the tank is easily accessed and made of a material that allows visual inspection, that satisfies the requirement. But if the tank is fiberglass, metal or any other material that's not translucent, a gauge is required. It is, however, a reg that's rarely enforced.

Jackdaw · Aug 2, 2015

Peggy, I agree that the newer electric gauges with external sensors are a lot more reliable.

I had NO idea about your 2nd USCG point. That's fascinating. Our factory tank is translucent but getting to it requires taking apart the vee berth. I'd rather count flushes.

PatTormey · Oct 2, 2015

Somebody here suggested a technique that I use..

Shine a bright light into the top of the poly tank and you can see the fill line.

Peggie Hall HeadMistress · Oct 2, 2015

The Profile tank level monitors are the best Profile Tank Monitors Also sold under the brand name SCAD Scad Tank Monitors

Available as either a 'solo' single tank monitor or systems that can monitor up to eight tanks. Sender goes on the outside of the tank, so need for any access to inside of the tank, and will work on any material except metal (they also have senders for metal tanks, fuel and water)...easy to install, highly reliable. Spend some time on the Profile seeing how they work. Dennis Ferriello, who's the mfr, provides the best customer service in the whole marine industry (I thought I was good till I met Dennis about 15 years ago!) and also drops in here to answer questions...I'll email him to monitor this thread.

OS2Dude said:
I recently purchased a 1985 Catalina 30 Mk I. The black water tank is BLACK plastic. (Polyethylene?) The only openings I can see are the input line, the vent and the pump out line. Currently the only way to know when it is full is when it overflows onto the deck and/or the contents spray onto the head port-light when you flush. (First time it was open, Such Fun! ) How does everyone else tell when it is full? I'd love a NMEA2K sensor, but the ones from OffShore Systems referred to in an older post need to screw into an existing access port. Any Ideas? (Fuel and fresh water sensors would be nice too. Fuel is aluminum and fresh is opaque white plastic.) Thanks!

py26129 · Oct 2, 2015

Jackdaw said:
You're on a lake. Just pump out often!

I think Peggy figures 3 gallons/day/person. ...........

I had not read that before but that makes sense. In fact, it may be a little generous. We are 4 on board (my better half, our two daughters and I) and we are good for about 7 days (49 gal. tank).

Can you hear the liquids splashing into the tank when you flush the toilet? Our tank fills from the top and, as the tank level rises the splashing noises get much quieter as the "drop" gets smaller.

Cheers

Matt

Peggie Hall HeadMistress · Oct 2, 2015

Jackdaw said:
Peggy, I agree that the newer electric gauges with external sensors are a lot more reliable. I had NO idea about your 2nd USCG point. That's fascinating. Our factory tank is translucent but getting to it requires taking apart the vee berth. I'd rather count flushes.

I don't think many CG inspectors know about it either. But it's on the books and you only need to run into ONE who does, and then you'd have no choice but to install a gauge.

Besides, counting flushes isn't all that reliable, especially when you have guests and/or kids aboard, 'cuz some flushes require more flush water than others...guests may use more than you would...and whoever is keeping track can miss a few. A single tank "solo" is only $135 including the sensor direct from Dennis and gives you a true 1/4, 1/2, 3/4 and full reading. A bargain at twice the price IMO.

Peggie Hall HeadMistress · Oct 2, 2015

py26129 said:
I had not read that before but that makes sense. In fact, it may be a little generous. We are 4 on board (my better half, our two daughters and I) and we are good for about 7 days (49 gal. tank). Matt

3 gal/per/day is pretty close... The average adult uses the toilet 5x/24 hrs. Avg flush is .6 gal--.5 (which is only two quarts) flush water, .1 waste...a bit more of both for solids. That comes out to an average of 3 gal/day. You CAN reduce that MAYBE a gal/day for two people, but you'd both have to do a lot of dry flushing.

Bob S · Oct 2, 2015

Peggy,

What's your opinion on the Seelevel II from Garnet Instruments?

https://www.garnetinstruments.com/rv-shop/

Peggie Hall HeadMistress · Oct 2, 2015

Bob S said:
Peggy, What's your opinion on the Seelevel II from Garnet Instruments? https://www.garnetinstruments.com/rv-shop/

I'd never heard of them before, so I did a little research. Not only is the sender attached to the outside of the tank, so are the electronics. My source--who owns an RV and has this system installed, btw--tells me that means that the tank walls must be as clean as a brand new tank for the system to work. He has to completely empty, then--using a chemical from them that costs $40/gal (or did he say quart?)--clean the tanks after about every 3-4 pumpouts.

So...knowing boat owners as well as I do :dance:...I don't TEEEENK it'll work well in marine applications. Interesting system, though.

Ron20324 · Oct 2, 2015

Some people say a stud finder will work, but I have not tried it.

Hello Below · Oct 2, 2015

Peggie Hall-HeadMistress said:
The Profile tank level monitors are the best Profile Tank Monitors Also sold under the brand name SCAD Scad Tank Monitors

Available as either a 'solo' single tank monitor or systems that can monitor up to eight tanks. Sender goes on the outside of the tank, so need for any access to inside of the tank, and will work on any material except metal (they also have senders for metal tanks, fuel and water)...easy to install, highly reliable. Spend some time on the Profile seeing how they work. Dennis Ferriello, who's the mfr, provides the best customer service in the whole marine industry (I thought I was good till I met Dennis about 15 years ago!) and also drops in here to answer questions...I'll email him to monitor this thread.

Very recently installed the Solo (Scad tank Monitor). Took maybe 2 hours, once I fabricated the mount. Very accurate and happy with the results.

Determining Black water tank level

.

.

.

.

.

Attachments

.

.

.

.

.

.

.

.

.

.

.

.