green slimy algae bloom #181383 - Ask Extension


green slimy algae bloom #181383

Asked May 13, 2014, 11:45 PM EDT

Awhile back a flock of abput 100 geese landed in my neighbors pond. After they left there seemed to be a massive algae bloom. It's thick, slimy and green. I thought the geese may have brought it in. Or is it a coincidence? What can I do to eliminate it and not kill the fish as I am afraid it will suffocate the fish?

Washington County Oregon

Expert Response

It may or may not be due to the "contribution of nutrients" by the birds.  Excess nitrogenous fertilizers applied to lawns that drain into the pond are another source.  However, the concern is how to control the  excess filamentous (slimy) algal growth.  The size of the pond is important due to volume of water, and the type of fish is important (trout and certain carp are more susceptable to recommended  treatments of relatviely lower cost copper based algicides that are recommended for filamentous algae control.  Your concern over loss of dissolved oxygen used by pond bacteria from treated decomposing filamentous algae (or just the probable decompostion of accumulated algae after completing their life) needs to be addressed.  A pond aeration system appropriate for the size pond would be a solution.  If a herbicied is used on the algae only treat 1/5 of the pond area every 2 weeks to allow for the pond to deal with algae mortality.  A chelated copper based herbicide such as one similar to Cutrine Plus can be sprayed on the algal mat.  Follow the directions.  New hydrogen peroxide based algal control chemicals are also available.
check the following website:

Brian Nerrie Replied May 14, 2014, 11:36 AM EDT

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