The last batch of plants that I ordered came with a surprise supply of string algae. So now it's growing on top of all my plants in the tank.

I've been trying everything I can to get rid of it. The farlowella I have in the tank seem to keep it off of the sides of the tank, but they can't seem to keep up with everything that's growing off of the plants. It's all dwarf hairgrass and other thin-stemmed plants, so I don't think that they can comfortably eat off of them. I've been considering getting some nerite snails to try and help, but I'm kind of assuming they'll have the same problem. The water in this house has copper in it, so I can't really get any shrimp.

I actually do have a UV filter on that tank. It's helped with a previous type of algae bloom I had, but it doesn't seem to do much for this type of algae. I've also tried to supplement the tank with some Flourish Excel, but I think because I don't have any broad-leafed plants in the tank that the plants don't use up the nutrients needed to starve the algae.

I've gotten rid of almost all of it before by putting goldfish in the tank. But they also dig up the plants and eventually destroy them if they're left in the tank for too long. And since the string algae is a single-cell organism, it only takes one leftover cell for it to eventually take over again.

Since the last time, all my plants were destroyed by the goldfish except for the large "clump" of java moss that's in the tank, I'm pretty certain that's where it's hiding in. I'm assuming that the goldfish could never get into the moss effectively to eat all of the algae.

The last thing I've tried was taking all the plants out, and rinsing them off, to try and wash away the algae, but it's back again. I can put the goldfish back in the tank to get rid of the algae, but I'd like to get rid of it for good.

Is there a way to get rid of string algae from hard to reach places like inside java moss?

  • If it was me I would tos the java moss in the bin. Keep a small part of it that seem to not be infested with algae and carefully watch it. I would keep it out of the tank in a bolw or some other container. when the tank is algae free but it back in. It will grown back in a couple of month.
    – Rémi
    Jan 27, 2016 at 15:45

1 Answer 1


I've successfully gotten rid of the algae by taking all my plants out and placing them into a quarantine tank, then dosing the tank with hydrogen peroxide for 3 days.

I'm not too sure on the specifics about how it works, but I found the solution suggested on some forums. A solution of 1 milliliter of hydrogen peroxide per 30 liters of water is supposed to be safe to use directly into a tank with fish in it. The hydrogen peroxide supposedly decomposes in light (which is why it's always in a dark bottle), turning into separate water and oxygen molecules after 24 hours. The reason I used a quarantine tank was because I couldn't find anything about it being safe for invertebrates.

After three days of dosing the quarantine tank, I could no longer see the string algae. And several weeks later it hasn't been growing back.

  • Glad to see you found a less radical solution than mine :)
    – Rémi
    Mar 3, 2016 at 16:46
  • @Rémi Yeah, I was keeping that as a last resort. It would have been a lot of java moss to throw away.
    – Spidercat
    Mar 3, 2016 at 17:11

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