Take a look at this thread, it discusses killing string algae with sodium percarbonate (which produces H2O2 when added to water) and hydrogen peroxide. Its a good read. When the barley straw breaks down it produces H2O2 same as peroxide or the sodium percarbonate.
http://www.koiphen.com/forums/showthread.php?t=53618&highlight=sodium+percarbonate+ponds
I have never had string algae, but it looks like peroxide would work fine if put directly on the string algae with an applicator, then remove the string algae.
For overall green water I would not recommend it. When I first filled my pond and got an initial algae bloom I tried peroxide, 160z per 1000gal is a safe amount I found online. Basically what happens is it will clear your water amazing for a few days, but all the dead algae will make a new bloom a few days later even larger because now it has food. Removing all of the dead algae to avoid a new bloom is almost impossible. Letting the pond cycle eventually takes care of it if you have adequate filtration.
If you have a good fines filter you can also add koi clay, which basically forms a big cloud of clay dust in the pond, clumps all the algae together, and you can then filter it out.
http://www.koiphen.com/forums/showthread.php?t=53618&highlight=sodium+percarbonate+ponds
I have never had string algae, but it looks like peroxide would work fine if put directly on the string algae with an applicator, then remove the string algae.
For overall green water I would not recommend it. When I first filled my pond and got an initial algae bloom I tried peroxide, 160z per 1000gal is a safe amount I found online. Basically what happens is it will clear your water amazing for a few days, but all the dead algae will make a new bloom a few days later even larger because now it has food. Removing all of the dead algae to avoid a new bloom is almost impossible. Letting the pond cycle eventually takes care of it if you have adequate filtration.
If you have a good fines filter you can also add koi clay, which basically forms a big cloud of clay dust in the pond, clumps all the algae together, and you can then filter it out.
