Catherine - For green filamentous or string algae do not use koi at this time. Try other methods first. Enough Koi numbers to reduce your algae will roil the water (murky or light mud colored) and make it less appealing for swimming. The murky water will reduce light penetration and reduce the amount of algae. Introducing Koi before bass are abundant will result in Koi over populating and then water will be muddier than when a few koi are present.

Regarding barley straw. Are you using adequate or proper amounts?. And are you introducing it early enough in the spring to be most effective before the algae becomes established.?

Have your tried Aquashade application early in the year? Although some do not like artificially blue water.

If you get your nutrient source under control, the consistant removal of green algae will result in less algae growth each year. If you are using the above methods in addition to aeration, a good bacterial program can also help in conjuction with the other "nonchemical" algae management methods.

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