Black tank

[Bohdan]

Greetings fellow rv’ers. Newbie here. Question about black tank. Monitor shows a “holding” tank is 2/3rds. I am assuming it’s black. Since the empty ones show gray 1 and gray 2 as empty. Along with fresh. If the gauge is incorrect how would one know. ? If I open the valve it may not be pleasant. Could only think P.O. couldn’t empty even though he emptied gray 1st. Thanks for your help. Cheers

[BFlinn181]

If you can reach the tank, thump on it. If it's 2/3 full, it would sound different than if empty. Level indicators are often wrong, especially black tank with materials left coating the walls making for false readings. Some toilets are directly over the tank, open the flush valve and look down to see if you can see into the tank. (turn off water pump first, no need to add water for just a look)

[redhooker]

It could be empty. I have never seen a black tank sensor set that worked beyond 1 year of use due to sludge on the walls of the tank. The sensors use the fluid to complete a circuit and illuminate each light on the panel, once a coat of good ‘ol stinky gets on the wall the circuit stays connected. They make better sensors that stand off the walls and help prevent that from occurring, but most experienced RVers just wait till the toilet “burps” for an accurate level reading.

You can fill the tank and put some dawn or degreaser in and allow to soak for a couple weeks, follow up with thorough rinsing for several hours, and it may fix the issue until the next time you use it and it starts all over again

I would also like to stress the importance of NEVER store or leave a black tank empty. Empty to me is 1/4-1/3 full to maintain a fluid tank bottom. Every dump I put in 10-20 gallons before I disconnect the flush hose. If you don’t have a santi flush just learn what a gallon looks like in the toilet and put 10 of those in after you dump. Dry black tank=poo cement that grows each use.

[BFlinn181]

I'd think 10 gallons after a dump to keep things wet is a bit much. In many RVs that would be 1/5 or more of the full tank. two or three should be plenty to keep things wet. A good tank cleaner is Calgone Water Softener. (powder) Used to find it at Walmart or order on Amazon, but it's gotten pretty pricey.

[DoC808]

Originally Posted by BFlinn181

I'd think 10 gallons after a dump to keep things wet is a bit much. In many RVs that would be 1/5 or more of the full tank. two or three should be plenty to keep things wet. A good tank cleaner is Calgone Water Softener. (powder) Used to find it at Walmart or order on Amazon, but it's gotten pretty pricey.

Powder? Now you tell me. I've been putting in the liquid. Oh well live and learn.

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[Bohdan]

Thanks . All good info. Speaking of leaving some water in the black tank, I suppose that this isn't a concern for freezing? Since it isn't full? Cheers

[BFlinn181]

Originally Posted by Bohdan

Thanks . All good info. Speaking of leaving some water in the black tank, I suppose that this isn't a concern for freezing? Since it isn't full? Cheers

If you leave a couple of gallons in the tank over winter, add a gallon or two of RV antifreeze to the tank. Pouring a bit of each gallon down each sink traps prevents them from freezing during storage too.

[Joe11]

Make sure you have that +/- 10 gallons of water in your black tank when you travel to help loosen “stuff”. Do that on your gray tank that services the kitchen sink too. You may be surprised what comes out.

[redhooker]

Originally Posted by BFlinn181

I'd think 10 gallons after a dump to keep things wet is a bit much. In many RVs that would be 1/5 or more of the full tank. two or three should be plenty to keep things wet. A good tank cleaner is Calgone Water Softener. (powder) Used to find it at Walmart or order on Amazon, but it's gotten pretty pricey.

My black tank is about 12 square feet. 8 gallons puts 1 inch of water on the bottom so I prefer a bit more than that but as you state each tank is different and we all have our own comfort “levels”

[saddlesore]

Originally Posted by DoC808

Powder? Now you tell me. I've been putting in the liquid. Oh well live and learn.

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Don't sweat it, I use the liquid and a bit of Dawn, does the same thing with the same results..
( I use the liquid because we have a vacuum pump toilet system and the powder can cause issues if it does not totally dissolve before the flush.)

[BFlinn181]

Originally Posted by redhooker

My black tank is about 12 square feet. 8 gallons puts 1 inch of water on the bottom so I prefer a bit more than that but as you state each tank is different and we all have our own comfort “levels”

1 gallon of water = 231 cubic inches. 10 gallons would be 2,310 cu. in. 12 square feet is 1,152 sq. in., so you're covering the floor of your tank with a little over 2 inches deep.

[redhooker]

Absolutely. You have calculated correctly so kudos to the math

Full timing with a family of 4 I dumped about once a week like this with a 75 gallon black.

[sbleiweiss]

No one has mentioned Happy Camper Extreme. It should clean his tank and let him start like new with sensors that work. Also, if OP has a tank spray system, use it after most dumps. They do a good job of keeping tanks clean too.

[DoC808]

Originally Posted by saddlesore

Don't sweat it, I use the liquid and a bit of Dawn, does the same thing with the same results..
( I use the liquid because we have a vacuum pump toilet system and the powder can cause issues if it does not totally dissolve before the flush.)

I can never find the powder. Tomorrow I'm heading to pick up some happy camper extreme to clean out the black tank. And probably use the other half of bottle in the gray tank

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