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Discussion Starter · #1 ·
Just got back from the boat, where I found a bunch of stuff in my water tank. I think I have a handle on what caused it, but lacking time to provide details. Meanwhile, have a look at this:

139649
 

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I assume there is ferrous iron in your water. That makes two general possibilities:

  • Air oxidized the ferrous to ferric, which is far less soluable, and it came out of solution as rust. It is also possible there is some iron in you system somewhere.
  • Bacterial film. The way it is "broken" at the far end suggests bacteria have formed a film. Bacteria can play a part in iron corrosion. They can also reduce iron in the pipes of your marina or the well to ferrous iron, which then apears as ferric iron in the tank.
So the answer is iron in the water and bacteria. I'm guessing it is not city, chlorinated water. But fill us in!
 

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Discussion Starter · #3 ·
I assume there is ferrous iron in your water. That makes two general possibilities:

  • Air oxidized the ferrous to ferric, which is far less soluable, and it came out of solution as rust. It is also possible there is some iron in you system somewhere.
  • Bacterial film. The way it is "broken" at the far end suggests bacteria have formed a film. Bacteria can play a part in iron corrosion. They can also reduce iron in the pipes of your marina or the well to ferrous iron, which then apears as ferric iron in the tank.
So the answer is iron in the water and bacteria. I'm guessing it is not city, chlorinated water. But fill us in!
I think it's the first, and hope it's not both. It's a long story that I'd like to tell when I have time. FYI, just before leaving the boat today I filled a clear cup with water right out of the spigot and added a couple drops of bleach. It immediately turned yellow, so that's a pretty clear sign that it's the ferrous-ferric oxidation that you mentioned. I also brought home a gallon water sample, which was clear at the time, but is yellow now just from the air exposure.

If you shock a rather tall 28 gal forepeak tank with chlorine, allow it to sit still for a couple days, and you get the intense red sludge that I showed. I seriously doubt it was bacteria, because I had thoroughly cleaned the tank to pristine condition just before doing the shock treatment.

There's more to tell when I have time.
 

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I think it's the first, and hope it's not both. It's a long story that I'd like to tell when I have time. FYI, just before leaving the boat today I filled a clear cup with water right out of the spigot and added a couple drops of bleach. It immediately turned yellow, so that's a pretty clear sign that it's the ferrous-ferric oxidation that you mentioned. I also brought home a gallon water sample, which was clear at the time, but is yellow now just from the air exposure.

If you shock a rather tall 28 gal forepeak tank with chlorine, allow it to sit still for a couple days, and you get the intense red sludge that I showed. I seriously doubt it was bacteria, because I had thoroughly cleaned the tank to pristine condition just before doing the shock treatment.

There's more to tell when I have time.
Interesting! That being the case, you have probably guessed that softening before filling is an option. Maybe the marina will listen.
 

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Discussion Starter · #5 · (Edited)
Interesting! That being the case, you have probably guessed that softening before filling is an option. Maybe the marina will listen.
It's a community dock, owned by the HOA. So I have to be careful to complain gently, since these will be my neighbors once my house is built, and I will also need them to approve my building specs before that.

It is well water. There is a water softener in the maintenance shed. The head of the dock committee says that they allowed the salt to run out and have fixed the problem. It will be about a week before I make it back to the boat, but I'll check it out as soon as I get back there. I'm going to do another bleach test on a small sample before I put their water back in my tanks.


Maybe I'll have a more quantitative test available to me this fall. My wife teaches an environmental chemistry course where they do a lab on detection of iron and lead in water. The next offering is coming up this fall. She used to have to travel up near a mine in central PA to get her test samples. Now she just needs to visit the boat! I came home yesterday and told her, "Look at this!" and she said, "I don't have to, I've seen that already this week." She was literally gathering equipment for this lab the other day.

My aft tank, which is very difficult to access, is currently empty (except for residual water below the hose barb). My forepeak tank, which has an easily accessible inspection port, is filled with water. It will be about a week before I make it back to the boat, but I'll look it over, clean out the front tank again, and go find some decent water. Maybe the HOA water will pass the test.

I'm really glad that I discovered this, because it's a heads-up that we'll need to design a top rate softening system into our future house. The guy on the dock committee says that iron removal is something that everyone there has to deal with.
 

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I can't believe I got that many guesses right on one thread!

As far as cleaning the tank, citric acid is probably the best choice. Good for iron stains, non-toxic, no weird after taste. Maybe you can reach a sprayer in there.
 

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you can get a screw water softener to attach to the garden hose you use for tank filling

I bet you don't really need to "clean" the tank, just flush it out.
 

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Discussion Starter · #8 ·
you can get a screw water softener to attach to the garden hose you use for tank filling
Been using one already. Doesn't work against this level of contamination.
 

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you will laugh, but I had high Ferrous content in my home in Bear Creek Twp, PA. Filled one of those inflatable ring 4 foot pools (yes I had a top of the line filter/iron filter/water softener on the house)... As soon as I added chlorine, the pool looked like coca cola. This was our drinking water (and yes it was safe to drink - and actually quite tasty). However, you get what you see there... rust fallout.

The only solution I have for you, is continuous filtering. In our pool we had to use an old TShirt, and wrap the filter, and spray clean out the rust stains daily for a week before the pool started to clear out.

Honestly its the chlorination that usually causes the iron to precipitate out (something you likely do to keep algae from growing in the freshwater tank, capful of chlorine - I know I do). If precipitates out black its manganese. Its ugly but its harmless.
 

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Discussion Starter · #10 ·
I can't believe I got that many guesses right on one thread!

As far as cleaning the tank, citric acid is probably the best choice. Good for iron stains, non-toxic, no weird after taste. Maybe you can reach a sprayer in there.
OK, I've finally got a good water source (long story, will share later) and have rinsed my tanks out thoroughly. There still seems to be a little amber color coming off the tank walls, but the inspection ports aren't large enough (or accessible enough) to stick my arm in and scrub. Having done all I can through rinsing, I think a citric acid soak may be my next step. What concentration do you suggest? What soak time? Thanks!
 
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