Forum Discussion

aarond76's avatar
aarond76
Explorer
Apr 08, 2013

Algae in Fresh Water Tank

Bought a used camper last spring. Would occasionally need to clean algae from faucets and would sometimes see it when flushing the toilet.

Winterized camper at end of year with antifreeze and drained fresh water tank.

Dewinterized today and an incredible amount of algae is coming from the fresh water tank. I have filled and drained three times so far and am bleaching heavy, using 1 cup for a 38 gallon fresh water tank. I found a water filter under the bath sink that did not have a cartridge in it. Bought a cartridge so no more algae thru the faucets and toilet but I can still see a large amount entering the filter.

The fresh water tank is under the camper, you have to crawl under to see it. There is a piece of black chloroplast under the bottom except for maybe 6" from the end where the drain is. The sides are exposed to light just as I would expect most of them are. I can see the algae on the exposed portion of the bottom of the tank. I do not see any growing on the sides. We live in MD and still had nights below freezing last week so I am surprised to see the tank full of green algae.

1) How can I kill it?

2) How can I get it all out of the tank?

3) How can I keep it from coming back?

I am surprised to have this much of a problem and never see any other posts about it.

8 Replies

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  • Phantom59's avatar
    Phantom59
    Explorer
    May 05, 2013
    I have seen this problem mainly when non clorinated water such as well water was used to fill the tank. I leave water in my tank and system year round with no problem. The RV is normally unused from October to April.
  • phillyg's avatar
    phillyg
    Explorer II
    Apr 08, 2013
    hilandfrog wrote:
    ...........Buy a water proof hatch cover, 5-6" (one with o ring) from boating store.
    Cut required size hole in fresh H2O tank,
    Mount hatch cover,
    Open hatch reach inside and clean out tank at the end of each season........


    X2. I don't think you can get rid of growth once it takes hold without scrubbing the interior of the tank. I recently had the same question and after speaking with a fella who had the same problem on his sailboat, he purchased an access hatch from West Marine and installed it in the top of his tank. Since you probably can't access the top of your tank, I recommend putting the hatch on the side of the tank. I would hesitate to put it on the bottom.
  • hilandfrog's avatar
    hilandfrog
    Explorer
    Apr 08, 2013
    I stole this idea from a guy over in the truck camper section a few years ago, did the mod this past year for Diddums...

    here is the link, did a quick picture guide on how I did it, you may find an easier way?

    http://www.rv.net/forum/index.cfm/fuseaction/thread/tid/25467063/srt/pa/pging/1/page/7

    Basic premise:
    Buy a water proof hatch cover, 5-6" (one with o ring) from boating store.
    Cut required size hole in fresh H2O tank,
    Mount hatch cover,
    Open hatch reach inside and clean out tank at the end of each season...

    Repo
  • skipnchar's avatar
    skipnchar
    Explorer
    Apr 08, 2013
    Fresh water SYSTEMS (not just the tank) should be sanitized at the very least once a year but ideally several times. With regular sanitizing with household bleach and filling the FW tank with a potable water source treated with Chlorine you should always have fresh clean water.

    To get the algae out that's already in there, open the valve on the bottom of the tank and drain and flush and drain and flush until it's clean. You may need to open the drain valve and take the trailer for a drive on a crooked road with lots of starts and stops also. MOST of them will not empty completely and that dark damp tank is a good growing spot for the problem. For that reason after I return from using the trailer the last thing I do is FILL the FW tank completely with treated water. When it's time to use it again, I drain and fill it with fresh potable water from city water source.
    Good luck / Skip
  • kedn's avatar
    kedn
    Explorer
    Apr 08, 2013
    I had the same problem after my trailer sat all summer, nice green crud. The problem I had was getting all the water (and algae) out of the fresh water tank. I got under and would push around on the bottom of the tank and try to get the water over to the drain, but then the problem was with the drain. The fitting stands up proud of the tank wall, so I never could get it all drained.

    I plotted how to get the tank free so I could tilt it or even how to make a different drain hole. Eventually I just made sure I bleached it good and rinsed good, filled it up and hit the road. We don't drink it, and I never noticed it come out the faucet, and it was all gone that I could tell when we got home.

    I haven't come up with a good way to drain the fresh tank completely.
  • krobbe's avatar
    krobbe
    Explorer
    Apr 08, 2013
    Use 1 cup unscented bleach for every 25 gal water. So just use 2 cups for your 38 gal tank. Flow it thru every line until you smell strong bleach odor at each faucet, toilet etc. Make sure the tank is completely full and let it sit for 24 Hours to kill it all. Flush the tank several times the next day to clear the bleach and dead algae. The 24 hours is pretty important to disinfect the tank. (I work in the water and wastewater industry)
    An open jug of bleach loses it's strength over time. So don't use last years half empty jug of bleach.
  • DiskDoctr's avatar
    DiskDoctr
    Explorer
    Apr 08, 2013
    Chlorine...how much are you using and how long are you letting it in the tank?

    With a rather strong concentration, you can tow it around a bit to slosh around and clean up the algae, like some do with ice in their black tanks.

    If you really have a lot, it is possible you have some sort of organic debris in the tank. Is the top or some other spot accessible? Make sure no dirt/moss got into the tank.

    Maybe it was filled from a pond at one time to get it started?

    Another thing to consider is using white vinegar instead of bleach.

    Soap (phosphorus) can feed and encourage algae in creeks, likely the same in the tank. Have you ever added any soap to the tank?

    Hope this helps.

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