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Old 23-01-2020, 11:23   #1
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Urine trouble now: scale from seawater and urine...

I have not had this issue personally, thanks to following Peggie Hall's comments WAAAAAAY back in the rec.boats.cruising time frame which are:

To avoid scale, pump 20 times after you've cleared the bowl, and then 20 times dry after you've done the flush.

While that doesn't entirely clear the line, if you're energetic and fast enough, most of the standing water is blown out over the anti-siphon loop, and, if your anti-siphon valve is working, you're left with a dry stack.

I've proven that on the times I've had to disassemble my PVC pipe ends for whatever reason (rebuild the pump, do something at the Y-valve), seeing nothing - at all - other than a very little dark stain (no body to it) at the very end.

However...

All that pumping does a number on the pump rubbers, and rebuilds are accelerated. For all the work I put into replacing hose with pipe, I surely don't want to do it again, but between the accelerated wear, and the admiral's (age induced? I dunno, but it's that way now) unenthusiastic half-dozen pumps, unless I go behind and do a thorough flush, I fear scale buildup.

I've seen hoses which have virtually closed due to scale. Of course, those most likely had not followed Peggie's regimen (it certainly worked for us!)...

So, the question - for any chemists out there - is, how long does urine have to be in sea water to precipitate scale? If I use the toilet (and do my Peggie Hall flush-and-dry routine) at least once a day, would that clear out any incipient scale, or would it have already formed? Is there ANY safe time for static urine-and-water to sit and/or is there a level of dilution which would alleviate that issue?

No, we can't flush with fresh water, as much as I know that eliminates the potential issue.

Thanks.

L8R

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Old 23-01-2020, 11:36   #2
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Re: Urine trouble now: scale from seawater and urine...

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Originally Posted by skipgundlach View Post
So, the question - for any chemists out there - is, how long does urine have to be in sea water to precipitate scale? If I use the toilet (and do my Peggie Hall flush-and-dry routine) at least once a day, would that clear out any incipient scale, or would it have already formed? Is there ANY safe time for static urine-and-water to sit and/or is there a level of dilution which would alleviate that issue?

Skip,
I'm a chemist, but not up on my urine scaling. This sounds like a great "at home" science project you could do on the boat.
Put urine in several glasses w/various dilutions of sea water, let sit for days and determine the amount of scaling.
Please report back w/your findings.


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Old 23-01-2020, 13:47   #3
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Re: Urine trouble now: scale from seawater and urine...

Not from a chemist, but my physicist husband says the flush must follow immediately after the urine. He may post, here, too, because I don't know his source.

The number of pumps varies from boat to boat, ours gets a complete flush out with 15 pumps, and you can hear bubbling outside after 10. You can use food coloring to determine the number of pumps.

With the situation you describe I'd think a trashed shoulder may be the cause for a lower number of pumps, something making it a lot more uncomfortable. One possible solution may be for you to flush for her, or you may need to shift to an electric toilet.

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Old 23-01-2020, 13:50   #4
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Re: Urine trouble now: scale from seawater and urine...

In my mind, this is mostly solvable with good plumbing design. I prefer feeding all heads directly to the tank and then providing a provision to pump the tank overboard if needed. No y-valves on the heads, so no direct discharge provision.

Doing this makes it easier to slope the hose from the toilet steadily downwards to the tank (or at least minimize any rise right after the toilet). As a result, it takes less water to fully clear the lines (which matters for the times where you need to hold waste for later, as the tank doesn't fill as fast).
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Old 23-01-2020, 14:31   #5
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Re: Urine trouble now: scale from seawater and urine...

As an ex water treater of cooling towers that experience the same scaling

The calcium and magnesium in the seawater will basically come out of solution right away if the concentrations gets high enough based on the high pH of urine. It is the pH increase of the urine that causes the problem and that why lots of flushing gets around it by diluting the urine. You can prevent any scale forming by lowing the pH and you can do this pretty cheap by having a squeeze bottle of diluted acid at the head. It is by far more effective to prevent the scale than to try to get it back out of the lines. Flushing acid through scaled lines doesnt work well because you can not get enough velocity to flush the scale out of the lines.
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Old 23-01-2020, 15:03   #6
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Re: Urine trouble now: scale from seawater and urine...

Sailorboy1, which dilute acid would you recommend?????

Thanks in advance for the info.

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Old 23-01-2020, 20:30   #7
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Re: Urine trouble now: scale from seawater and urine...

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Sailorboy1, which dilute acid would you recommend?????

Thanks in advance for the info.

Ann
Any acid would work, even vinegar. If you were going to this on a consistent basis probably the cheapest would be muric acid/ hydrochloric acid from the hardware store made down to a 10% solution. Just give the head a spray bottle squeeze each use.
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Old 23-01-2020, 20:39   #8
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Re: Urine trouble now: scale from seawater and urine...

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Sailorboy1, which dilute acid would you recommend?????

Thanks in advance for the info.

Ann
Vinegar is very commonly used for this.
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Old 23-01-2020, 20:51   #9
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Re: Urine trouble now: scale from seawater and urine...

Sailerboy1 I think urine is normally slightly acidic. I wonder if anyone has actually done a chemical analysis of the scale in sewage hoses on boats?
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Old 23-01-2020, 20:51   #10
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Re: Urine trouble now: scale from seawater and urine...

Seawater mineral and urine crystal buildup can easily be prevented by flushing a cupful--2 cups at most--of undiluted distilled white vinegar all the way through the plumbing once a week. Followed by a about a quart of clean FRESH water after 45 60 minutes.


Despite claims to the contrary, distilled white vinegar CAN dissolve the buildup, but because the vinegar has to be replaced every couple of hours multiple times (which nobody who claims it won't work ever does), it's more labor intensive than it's worth when muriatic acid can do it with a single application--maybe two--allowed remain in the plumbing for about an hour. Follow with a thorough fresh water rinse.



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Old 23-01-2020, 21:11   #11
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Re: Urine trouble now: scale from seawater and urine...

Thanks, Sailor Boy and Minggat.

Sailor Boy, muriatic acid is expensive in Oz, where we are, and vinegar is dead cheap and easy, too. So now I have another question: how much vinegar into the bowl for, say, 350 ml. of urine? Also, what kind of spray bottle would you use? Like for ketchup? or more like bathroom sprays?

And, thanks so much for the help.

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Old 23-01-2020, 22:09   #12
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Re: Urine trouble now: scale from seawater and urine...

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Sailerboy1 I think urine is normally slightly acidic. I wonder if anyone has actually done a chemical analysis of the scale in sewage hoses on boats?
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According to the American Association for Clinical Chemistry, the average value for urine pH is 6.0, but it can range from 4.5 to 8.0. Urine under 5.0 is acidic, and urine higher than 8.0 is alkaline, or basic.
..........
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Old 24-01-2020, 00:57   #13
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Re: Urine trouble now: scale from seawater and urine...

Every two weeks I would put a cup of vinegar in, flush a couple of strokes to get the vinegar in the pump and lines, close the thru hull, and go to bed for the night. Of course my standard rule is to flush 10-15 more strokes after everything is clean.
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Old 24-01-2020, 05:51   #14
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Re: Urine trouble now: scale from seawater and urine...

Quote:
Originally Posted by peghall View Post
Seawater mineral and urine crystal buildup can easily be prevented by flushing a cupful--2 cups at most--of undiluted distilled white vinegar all the way through the plumbing once a week. Followed by a about a quart of clean FRESH water after 45 60 minutes.


Despite claims to the contrary, distilled white vinegar CAN dissolve the buildup, but because the vinegar has to be replaced every couple of hours multiple times (which nobody who claims it won't work ever does), it's more labor intensive than it's worth when muriatic acid can do it with a single application--maybe two--allowed remain in the plumbing for about an hour. Follow with a thorough fresh water rinse.



--Peggie
Hi, Peggie, and thanks for turning us on to the multi-pump solution all these years ago.

As to the muriatic acid, we have some, coincidentally, left over from cleaning the bottom of our dinghy.

However, we have Raritan PHII toilets aboard. In the time we've owned them, both have had bases fail (one each) and multiple pump failures, due to fractures (not breakage - just splits enough to leak).

That's both expensive and a bloody nuisance to deal with. Our pumping routine has kept us clear, but before we had our breakage issues, we did, indeed, occasionally put some muriatic down the pipe.

Raritan has cautioned strongly against using household cleaners, and by inference, anything approaching muriatic acid, or even Barnacle Buster.

As you have an industry background, can I take your recommendation to mean that muriatic acid is safe for marine toilets and downstream hose/pipe?

(You'll recall we replaced our hose with PVC and could not be happier with that decision...)

Thanks for your continued support of our sanitation education!

L8R

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Old 24-01-2020, 06:06   #15
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Re: Urine trouble now: scale from seawater and urine...

Hose out of my system 2 weeks ago during replacing the head. This system has had a lot of acid flushed through over the years. As you can see it has a LOT scale. Yes acid will dissolve it. But a standard head pump does not have the velocity to take it out of the hose so it reforms. Im sure it would probably work if there are no low spots, but that is possible for everyone.

This is why i feel the best answer if using seawater flush s the small amount of acid each use.
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