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Old 03-14-2014, 02:56 PM   #1
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Tank Capacities

This is likely the wrong section to enter this, so bear with me.
It seems to me that both my black and grey water tanks get full in short order and when I drain them, it goes a lot faster than it should. I've just had this rig for a little over a year so I have no idea how the previous owner/owners did things. Is there any formula which would allow me to get a WAG on how much stuff is flowing in a particular period of time. I thought that I could dump both and then fill them both with the rated gallons (60gal grey/40gal black) and see how close the levels are to top. Labor intensive but I could find out if any crap/gunk is taking up room.


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Old 03-14-2014, 03:24 PM   #2
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Your proposed method should work. I have a flow meter that goes on any hose and measures volume flow through. If you use a flow meter and put the hose in the sink or toilet as appropriate, you should be able to measure how much water goes into the tank. The flow meter was not expensive.

Good luck,

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Old 03-14-2014, 03:45 PM   #3
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You might try one of these: Amazon.com: AbsolutelyNew Water Saver Usage Meter: Patio, Lawn & Garden

Also, if the black tank was abused by previous owner, you might have a 'pyramid of doom' built up in it. Try the GEO method to clean it out. https://sites.google.com/site/cbruni/

Calgon Water Softener is often hard to find in the stores, but Amazon sells it. With the water meter, it would qualify for free shipping!

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Old 03-14-2014, 03:56 PM   #4
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Put the waste cap on that has a hose connection and fill waste tanks with water. Then dump into 5 gallon bucket until empty.
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Old 03-14-2014, 04:43 PM   #5
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Or... Could fill that 5 gallon bucket with your hose and time how many minutes/seconds it takes to fill it. If a it took 2 minutes to fill, then a 40 gal. tank would be 40/5=8X2=16minutes to fill. Would get you pretty close but I'd have someone watching that hole in the throne just in case you have some solid water displacement that's not suppose to be there.
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Old 03-14-2014, 05:18 PM   #6
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And of course if you are relying on the usually faulty gauges (lights) to let you know when the tanks are full, you might be led astray. Tank filters are notorious for giving wrong (usually too full) readings due to obstruction at the sensors on the inside of the tanks. You should be able to find some possible cleaning tips around this forum.
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Old 03-14-2014, 05:26 PM   #7
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The grey tank should not have a pyramid of stuff. If the black tank does it should clog or severely impeded dumping.

I dont look at the gauges. I hate liars.
I do not gauge how much has been brought aboard nor how much is dumped.

I dump every 5-7 days, or when one of the tanks gurgle. Then I dump them both.
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Old 03-14-2014, 08:06 PM   #8
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How do you know when the tanks are full? "The BURP method works." Most gauge lights are not accurate.
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Old 03-14-2014, 10:45 PM   #9
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To get all the water out of my tanks, I have to put blocks under my front jacks and jack it all the way up. My driveway is on about a 5% grade. Found out the hard way when my black and grey tanks filled sooner than expected.
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Old 03-15-2014, 07:50 AM   #10
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As mentioned above, I think the "filling a 5 gal bucket" method is as easy and as accurate as you can get.
If you dump your black tank first, then fill with water, you should get a good idea of the condition by watching what drains into the 5gal bucket

I need to do this too...just been too busy. I think my fresh water indicator is fine, because I can visually see the level of water in the tank and it matches what's on the panel. Gray doesn't seem to be a problem either. Black I have no idea, and really need to check. PO had the coach repo'd, so who knows what was in the tank and how long it sat.

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Old 03-15-2014, 10:43 AM   #11
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Other thing I forgot to add to my first post here is, I always put a short section of clear drain pipe on when dumping. That way I can see if the tank is running clean after dumping and running tank flushers for a few minutes. If you continue to see anything other than water running out slinky, you know further cleaning is needed. An acurate reading on fresh water tank doesn't mean sensors in black and gray tanks are reading accurately.


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