Pond algae problem

[brucen]

Hydrogen peroxide starts to work in minutes and only lasts for a few hours, so it's effects are very short lived. It oxidizes, creating more oxygen, then it's gone. The water won't harm other plants or animals.

In my opinion, draining and cleaning the pond is adding to the problem. Algae is a result of too many nutrients in the pond. There is bacteria growing on all hard surfaces of the pond and in the filter. That bacteria also feeds on those nutrients. Given time and the right conditions, enough of that bacteria will grow to outcompete the algae and the algae will die off. But every time the pond is drained and cleaned, those bacteria are being destroyed so the algae wins.

If this were my pond, I would put up a shade sail or use some other means of shading it. Algae needs sun. It doesn't grow well in the shade. I would add lots of plants to also use those nutrients. I would stop draining the pond and allow it to find it's own balance. Just my opinion.

Thank you for your reply. I will keep the idea of using hydrogen peroxide in mind. But I tried a different, copper based, algaecide. Even though I have a Ph.D. in Microbiology (gee, one would think I would know how to kill algae) but my calculations on how much to use which was based on acre ft were off buy 10 fold. That is, I added 1 cup when I should have added only 0.12 cups. But this may have been fortunate. The result (since the algaecide is a dark blue) was that the water in my pond (water feature) turned a deep but beautiful ocean blue. Not what I had intended but the algae quickly began to disappear. After several days with the dense blue water, I drained the pond, rinsed it, refilled it and added just 2X the recommended amount of this algaecide. It has been three days and no algae whereas, before, I could see algae after just one day. We shall see how long this algaecide works. But thanks for the tip about hydrogen peroxide! I will try this in the future.

 

[Lisak1]

I'm glad you resolved your issue - but know that it's just temporary. A pond with no plants will continue to grow algae forever. A regular dose of algaecide will keep it clear but you'll need to keep on a schedule with it.

Were you not concerned that emptying the algaecide would harm the surrounding plants like you were about the H2O2?