white film in freshwater hoses

[iotum]

I had to replace the galley faucet because it inadvertently got a good whack and started leaking. When I pulled the hose off of it that comes from the foot pump, I discovered that there was a white film inside the hose. See attached pic.

This was a bit alarming and I found the same film on the other water hose (tank -> pump). I did not find any film inside the tank itself. I drained the tank by pumping out through the faucet hose with the faucet removed and without the restriction of the faucet the flow rate was much higher and some of the film flaked right off.

I replaced the hoses and flushed the entire system with a mild bleach solution and then lots of water, but I'm curious if anyone has seen this before and knows what it is or how to prevent it from coming back. I'm assuming it's some kind of algae or mold or something, but the pure white color threw me off.

[Tsuru]

I get something similar in my potable water lines. I believe it is minerals precipitating from hard water.

[LAGERTHA]

Sorry to say, that after 30 yrs tinkering with boats...I never seen this before. Curious to know if it was solid white substance? Any chance that maybe it was purposely part of the fresh water hose as manufactured? Did you check a different fresh water hose, say at the head sink to see if that fresh water hose also has that white coating?

[iotum]

Originally Posted by LAGERTHA

Sorry to say, that after 30 yrs tinkering with boats...I never seen this before. Curious to know if it was solid white substance? Any chance that maybe it was purposely part of the fresh water hose as manufactured? Did you check a different fresh water hose, say at the head sink to see if that fresh water hose also has that white coating?

Good thought, but it's definitely not original to the hose. I replaced it with more of the same exact hose (leftovers from original install) and it's not present on the unused hose.

It's solid-ish... it came off in flakes but the flakes seemed flexible. I still have the hose I removed and now that it's dry it comes off easily when you scrape it with a pick.

[iotum]

Originally Posted by Tsuru

I get something similar in my potable water lines. I believe it is minerals precipitating from hard water.

I sure hope that's all it is, and that would make sense with the bright pure white color. Any idea about how to prove that's what it is?

[wholybee]

I've never seen it so white. I've seen off white, brown, and green. Those colors would indicate algae or bacteria. Most likely a bacteria, because algae needs light to grow. But that bright white, maybe it is something else.

Treat it with a less mild bleach solution, and let it sit in the hoses a day. Then rinse. After doing this, mine cleaned out, but I had to take the aerators off all the taps to flush because they clogged. Then, add a bit of bleach to every tank of water to prevent future growth.

[Jammer]

It's scale. A calcium precipitate common on the inside of pipes/tubing/hoses in hard water areas. Whether and to what extent you get it depends on the local water chemistry. High pH water with high hardness (calcium content) produces it, and this is common in areas that use groundwater sources from limestone-rich aquifers.but

It's harmless. You can remove it with acid if it offends your sensibilities.

[iotum]

I did an experiment, taking a short section of the hose and leaving it in vinegar to see what it did to the film. After a few days the film all flaked off but it didn't appear to dissolve so I'm thinking that suggests it's probably some kind of growth and not scale. I guess it's also possible that I just saturated the vinegar, but I'm not sure how I would check that.

[Tin Tin]

It looks like calcium build up. Vinegar soaking will fix it. Citric acid may do a similar job.

[Kelkara]

Originally Posted by iotum

I did an experiment, taking a short section of the hose and leaving it in vinegar to see what it did to the film. After a few days the film all flaked off but it didn't appear to dissolve so I'm thinking that suggests it's probably some kind of growth and not scale. I guess it's also possible that I just saturated the vinegar, but I'm not sure how I would check that.

You want to test with hydrochloric acid ... dry it out, then drop the acid on, Calcium Carbonate produced by precipitation from hard-water should visibly fizz producing CO2 when it comes into contact.