Shower sump crud

[osprey877]

Attached below is a picture of my shower sump. I don’t use the shower so I’m pretty sure the water in it is what drains down from the inside of my mast. The water in the sump is clear and fresh and there is no smell, but there is a fairly thick deposit of reddish brown crud that coats the sump, the pump, switch etc. It looks brown in the photo but is actually a rusty red colour. What is this and is there any way to stop it forming? It cleans up fairly easily but is somewhat staining and a PITA to get all the hoses etc clean, only to have them foul up again. Is it a fungus, or dissolved minerals or?? The mast is aluminum with as wire halyards if that helps.

[thinwater]

Harmless bacteria. You'll see the same thing around shaded stagnant puddles.


I'm not sure there is anything you can add that will kill it and be safe to discharge and not damamge the equipment. The staining is due to the rusty, non-stainless screws in the hose clamps. Those I WOULD do something about, because they will fail soon. The bacteria are drawing iron from the water, oxidizing it, and causing the characteristic staining. But the non-stainless screws are the root cause.



Just ignore the bacteria, if there is no smell. It's a boat.

[a64pilot]

There is something you can do about it.
I had a smelly bilge from fresh water being in it. Of course chlorine will kill anything, but it is also not safe for metals and other things in my bilge, and it’s a temp solution as it off gasses.
A member here who was I believe a water treatment pro told me to use air conditioner condensate tabs. It works and I don’t think it off gases, and I assume the ones approved to be used in a computer room aren’t corrosive.
These are the ones I have, I didn’t buy them here most likely Amazon.
https://www.supplyhouse.com/Nu-Calgo...xoCWM4QAvD_BwE

[sailorboy1]

You can find the tablets pretty much any hardware store.

One thing about it is that it’s a non-oxidizing biocides and bacteria can become resistant to it over time. If you have a spot on the boat that is regularly having this problem it would probably be a good idea to do a bleach flush once in a while (spray down with a bleach mixture and allow to sit an hour and then flush and rinse with dread water)

[osprey877]

Originally Posted by thinwater

Harmless bacteria. You'll see the same thing around shaded stagnant puddles.


I'm not sure there is anything you can add that will kill it and be safe to discharge and not damamge the equipment. The staining is due to the rusty, non-stainless screws in the hose clamps. Those I WOULD do something about, because they will fail soon. The bacteria are drawing iron from the water, oxidizing it, and causing the characteristic staining. But the non-stainless screws are the root cause.



Just ignore the bacteria, if there is no smell. It's a boat.

I am using what are claimed to be stainless steel hose clamps. Are the screws not stainless also??

[osprey877]

Originally Posted by a64pilot

There is something you can do about it.
I had a smelly bilge from fresh water being in it. Of course chlorine will kill anything, but it is also not safe for metals and other things in my bilge, and it’s a temp solution as it off gasses.
A member here who was I believe a water treatment pro told me to use air conditioner condensate tabs. It works and I don’t think it off gases, and I assume the ones approved to be used in a computer room aren’t corrosive.
These are the ones I have, I didn’t buy them here most likely Amazon.
https://www.supplyhouse.com/Nu-Calgo...xoCWM4QAvD_BwE

Thanks for the tip. I have just ordered a jar of 200 tablets from amazon. How many tablets do you use and how often do you change them?? It rains a lot here in the PNW so the water in the sump should be turning over pretty regularly.

[sailorboy1]

1 tab every couple weeks should be enough

The screws on those SS clamps may not be SS. Iron reducing bacteria can cause a lot of corrosion even to SS.

[Bill O]

Not unusual to have high iron/steel screws w/a SS band. Always check the screws w/a magnet.


Bill O.

[thinwater]

I was well aware of non-oxidizing antiseptics, such as the BAC (benzalkonium chloride) used in the tablets. I've designed commercial wastewater plants to degrade BAC waste. Its marine toxicity is rather high and it is not good to release it into a marine environment. Hardly a disaster in tiny amounts, but not a chemical I would use in that way. That's all.



That is why I did not mention it. I would just ignore the bugs if they are not causing a problem. The OP said it did not stink.