string algae and winter

kimbra8November 8, 2008

I think I read somewhere that it is good to have string algae in the pond over winter but can't remember the reason behind it.. I have some now and the fish don't seem to be keeping up after it and was thinking of doing a treatment but I have a memory of reading somewhere it might be beneficial to leave it this time of year.. Any thoughts?

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knotz(8/PNW SWWA)

I've got it too and would like to know :)


    Bookmark   November 8, 2008 at 6:11PM
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I have it too, and I've been using a toilet scrubber to get it out. The fish don't seem interested in it.

    Bookmark   November 8, 2008 at 9:47PM
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horton(6 b Ontario.)

String algae thrives in cooler water, especially when it does not have to compete with other plants for nutrients.

If you want rid of it, either you have to pull it out, using a toilet brush or a stick to roll it around.
Or treat it with Hydrogen Peroxide 3%.
Just pour the HP directly over the string algae. In a day or so drag the dead brown algae out of the pond.

The rule of thumb dosage of HP is, one pint per 100 gallons of water once a week. I use a couple of bottles, poured over the string algae, when needed and it works out just fine.
If you have a 500 gallon pond you don't need to use five bottles of HP. Just treat the area where the string algae is growing. Repeat the next week if required.

HP will add oxygen to your pond water and will not harm fish or other plants, as long as you do not go crazy with it.

    Bookmark   November 9, 2008 at 8:04AM
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But should it be left in over the winter as a food source for the fish, or will we regret leaving it in come spring? I have some as well, not alot, and I am surprised that I actually like how it looks on the sides, all flowy with the water movement, lol. Prob cuz I dont have alot of it, if it goes crazy I'll prob hate it, lol. But will it go crazy come spring? Will it die overwinter?

    Bookmark   November 9, 2008 at 9:24AM
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If you have a little over the winter it will be good for the fish to eat. Will it die over winter? Depends on how cold the pond gets, if it freezes and to what extent. In zone 5 my string algae starts up in early spring with the pond having a solar floating pond cover on.

Will it go crazy come spring? Most likely yes, and this can be helped by a good cleaning and some small frequent water changes and good filtration as the season progresses.


    Bookmark   November 9, 2008 at 2:34PM
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horton(6 b Ontario.)

Lisa said it all!

    Bookmark   November 9, 2008 at 9:18PM
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johnkr(z5 PA)

I like to leave some string algae in the pond during the winter months. My fish will eat string algae when there is no other food available. Especially in the early spring.

String algae will also compete with suspended algae while your plants are still dormant. I remove most of the string algae after my plants begin to sprout.

    Bookmark   November 10, 2008 at 11:45PM
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I knew there was a reason to leave it in.. Thanks to all and have a safe and warm winter... Can't wait till spring to get back out there..

    Bookmark   November 11, 2008 at 8:24PM
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If the string algae grows from floating leaves, can I still pour hydrogen peroxide over the water?
And sure it does not harm the tender seedlings?

    Bookmark   November 13, 2008 at 12:04AM
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horton(6 b Ontario.)

Tarja, I have used HP many many times and I have never known it to harm anything, other than string algae.
It will not even harm suspended algae in the water.

    Bookmark   November 13, 2008 at 7:20AM
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Never rip string algae out because this will cause the algae spores to detach from the algae and encourage future growth. Either hold the algae and cut it out with scissors, or twirl around a stick to grab all of the algae.

more at

Here is a link that might be useful: Algae answers

    Bookmark   November 14, 2008 at 5:39PM
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After reading that link supplied by pacoutdoor I am now wondering if what I have been calling string algae is actually surface algae... I am just letting whatever it is in there.. Thanks for the was helpful

    Bookmark   November 15, 2008 at 7:44AM
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no problem, glad it helped!

    Bookmark   November 20, 2008 at 6:07PM
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horton(6 b Ontario.)

Barley straw produces hydrogen peroxide, as it decomposes in the water, that is why it is used for algae control.
And that is also why you have to wait two weeks or more to see results.
Buying a bottle of HP is much cheaper and quicker acting, than a "bail" of barley straw.

    Bookmark   November 21, 2008 at 6:45AM
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GreenClean is an algaecide that works in the same manner as Hydrogen Peroxide as it is similar chemistry and it is not known to harm anything other than algae, so I assume regular hydrogen peroxide would be safe also. The nice thing about GreenClean for spot treatments is it is granular so it is easy to target specific areas.

I dont know if your pond freezes over or not, but it probably wouldn't be a good idea to do an algae kill prior to your pond freezing or even before the water gets too cold. That dead algae sitting at the bottom of your pond could create ammonia during the winter, unless you remove it after it dies.

Here is a link that might be useful: GreenClean

    Bookmark   December 3, 2008 at 5:44PM
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