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Old 24-01-2018, 22:37   #46
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Re: How do you keep your toilet pipes clear

Sea water mineral buildup only occurs in plumbing connected to sea water toilets on boats in salt water. So, yes, following every sea water flush with a bowlful of fresh water can prevent it or at least slow it down a lot, but it won't remove it and it's not always practical to do that. Post #4 in this thread covers how to prevent it and the most common cure for it.

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Old 24-01-2018, 23:22   #47
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Re: How do you keep your toilet pipes clear

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Originally Posted by ZULU40 View Post
these are not unrelated topics, they are the same topic
Yes (mineral deposits and other inputs to a boat's sewerage system are related). And no (they are not the same topic).

Consider the problem of limescale deposits in other parts of the boat, such as:

* limescale deposits in engine heat exchanger;
* limescale deposits in shaft tubes, such as associated with shaft seals and shaft bearings (e.g. cutless bearings);
* limescale deposits in exhaust mixing elbows;
* limescale deposits around external (to the hull) heat exchangers;
* limescale deposits on the external surfaces of portlights;
* limescale deposits on metal fixtures (e.g. rudder posts, deck hardware).

What these have in common with mineral deposits in the sewerage system is one important factor:

* seawater is saturated or supersaturated with calcium ions and others calcium anions (including calcium carbonates, calcium sulfates, calcium magnesium carbonates) and with high concentrations of a few others (such as calcium phosphates).

That supersaturation with calcium explains why sea animals (everything from protozoa to molluscs and crustaceans) can very easily make shells and internal objects from calcium carbonate and/or calcium magnesium carbonate (with other inorganic and organic components).

That supersaturation explains why the first precipitation from seawater is calcium carbonate and calcium magnesium carbonate, not sodium chloride. Try it for yourself: get a cup of seawater. Let it evaporate (raise the temperature to speed the process).

Even before the water level has dropped 50% you'll see whitish deposits on the wall of the cup. You'll see it on your stanchions, your portlights, etc.

Only when about 75% of the seawater has evaporated from your cup will you find NaCl crystals (sure, you'll find salt crystals on your stanchions and portlights too, but long after they're coated with a haze from CaMgCO3).

Take seawater and warm it. Such as in an engine heat exchanger. Or your shaft tube after you've anchored or docked, as the prop shaft cools down. Mineral deposits, those same CaMg-carbonate deposits start forming because the solubility of calcium carbonates falls with an increase in temperature.

For that matter, landlubbers who use freshwater with a moderate calcium level will have noted that the heating elements of some kettles and water heaters get coated with limescale. Same reason. Sidenote: and if you happen to live with a low level of calcium dissolved in your drinking water, you're at higher risk of heart disease and so on!

Add some urine to the seawater. Your kidneys are excreting some calcium each and every day. That extra calcium, plus other chemicals in urine, add to the supersaturated calcium carbonate load of the seawater.

Let the urine and seawater solution sit around for a while. Bacteria (in the seawater and in your urine. Back in the 1950s people used to think the urine of human males was sterile (in contrast to the urine of a female, with shorter urethra. But that myth was exploded once microbiologists realised that they were just trying to grow urinary bacteria in conditions in which those bacters were not happy) grow. And cause chemical changes that cement the calcium magnesium carbonate into a concrete, with inclusions of uric acid.

Add some human faeces. About 70% bacteria (by dry mass). More bacteria and more nutrients for other bacteria that add to the concrete deposits.

It's that concrete, that mix of calcium magnesium carbonates + uric acid + chelates with lots of other inorganic and organic chemicals, which is the mineral deposit. And that concrete can resist low pH, or is a lot more resistant than what you see when you drop HCl and especially a weaker organic acid such as acetic acid on pure calcium carbonate.

So yes, it's all related.

But no, the limescale deposits can occur without your urine and faeces.

The urine is big contributor to the problem. The faeces less so.

Quote:
Originally Posted by ZULU40 View Post
I would contend that the subject causes had evolved, and that adequate flushing is a reasonable fix.
Adequate flushing is better than inadequate flushing, by definition. One question is whether any level of flushing with seawater is adequate in the long run to prevent mineral deposits.

Flushing with freshwater is not a bad idea. For boats that have regular docking, flushing with freshwater so the sewerage system is left soaking in freshwater is a good thing. But while cruising or otherwise being away from cheap and abundant freshwater, there's a problem.


If you talk to people who deal with urinals in public toilets, you'll find that flushing human male urine is not that simple even with freshwater unless the freshwater is cheap and abundant.

Urinals are however a step forward. The lack of separation of urine from faeces in the design of water closets was probably an error. If the urine is kept separate, reclaiming phosphates is relatively easy.

So excluding urine from a boat sewerage systems is not a bad idea. Hard to accomplish in some cultural and social settings.
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Old 25-01-2018, 00:10   #48
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Re: How do you keep your toilet pipes clear

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Originally Posted by Akapeterc View Post
I just had to replace the outlet pipe on my toilet it was all calcified up completely blocking it anyone have any great ideas of how to keep the pipes from blocking up after a couple of years besides fresh water flushing?


This is a good part of your solution.....
https://www.amazon.com/SonTiy-Handhe...t+sprayer+head
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Old 25-01-2018, 01:04   #49
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Re: How do you keep your toilet pipes clear

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Originally Posted by Emerald Sea View Post
This is a good part of your solution.....
https://www.amazon.com/SonTiy-Handhe...t+sprayer+head
I'd suggest:

https://www.ebay.com/p/Unisex-Portab...tle/1276294911

or

https://www.westmarine.com/buy/littl...11_334_007_500
(and add the Lady Jane option)

Even in land sewerage systems, urine mixed with faeces pushes the pH towards the alkaline, so likely a pH of 7.5 to 8.5.

The higher the pH, the more CaMg carbonates will precipitate from seawater as mineral deposit.

To minimise the Ca-Mg-CO3 cement, you want a lower pH (or a lower concentration of seawater, or a lower temperature)
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Old 25-01-2018, 08:28   #50
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Re: How do you keep your toilet pipes clear

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Originally Posted by Alan Mighty View Post
Adequate flushing is better than inadequate flushing, by definition. One question is whether any level of flushing with seawater is adequate in the long run to prevent mineral deposits.

Flushing with freshwater is not a bad idea. For boats that have regular docking, flushing with freshwater so the sewerage system is left soaking in freshwater is a good thing. But while cruising or otherwise being away from cheap and abundant freshwater, there's a problem.
ok so I felt I had to prosecute what I apparently should have said all along, 'adequate flushing'

My intention was to suggest that people used to land based systems where one has for the mostpart abundant water to flush, and normal land based systems use quite a lot. The difference then is that the plumbing on a sailboat system is more restrictive, and doesnt operate under the same water pressures.

Might be worth adding that Zaya's system doesnt have a holding tank, so isnt used where its not legal to do so. Where it can, I have an ocean of water to use. Might also be worth mentioning that Im not sure newer boat owners would be given the same latitude as I seem to have been allowed.

So 'adequate' describes much longer flushing period that guarantees water from the raw water inlet will be flushed all the way to the hull outlet. We have a longer tract to take care of and I wanted to emphasise you arent simply flushing the head and what you can see, but the entire tract which you cannot. As an example I run mine for around two minutes and my tract might be around 3 metres long including the anti-syphon system. Its the same process when the boat hasnt been used for over a week and de-oxygenated seawater has been locked into the system in the dark. Im pretty sure I can safely pump that overboard on the way out of the river, but I might be chancing my luck.

These particular thru hulls were replaced just a few months ago and there were very limited mineral deposits throughout the system.

For the record I didnt mention fresh water, although it sounds like a good idea.
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