I know barley balls are used in outside fish ponds to control algae can they be used


Junior Poster
Mar 16, 2007
question; I know barley balls are used in outside fish ponds to control algae. The barley rots and releases hydrogen peroxide, I think. The h202 is what prevents the algae from growing. If i am wrong I am sure I am gonna hear about it. :) If this is true can you put a barley ball in an external hang on filter for your fish tank. Will it work to help control algae. I am going to set up a planted aquarium this is one of many questions.

thanks Brian

Tom Barr

Staff member
Jan 23, 2005
I've discussed this many times and few researchers bother with this these days, back in the mid 1990's a few did and the results where mixed.

In England, it looked good, in the states, we found much less utility.
Likely due to higher temps(like in our tanks), and more sunlight, and more plants, shallower ponds.

If you use it for phytoplankton control, that's one thing, we do not have issues with GW in our tanks generally if the tank is set up right to begin with.

Most pond owners simply use a UV to deal with GW.

Now about attached algae, no one has show that it does anything there.

See the articles listing here for more about barley straw, I'm not interested in rotting straw in my tank personally. Also, it's speculation that it's H2O2. If that is the active ingredient, why not add that then?

I think it's more to do with bacteria needing a carbon source and surface to grow which in turn support other organisms that feed on the bacteria and the zooplankton that eat those and the algae.

Excel works far better and adds something the plants can use.

Rather than worry about algae, try worrying about plant health.
You'll get much farther.

Tom Barr