Green Algae: It's Big, Green, And Wants To Eat Your Water Garden!

Sunday, September 23, 2012

By Keith Klamer


It's the bane of backyard ponds all over the country: sometimes called "green water", "blanket weed", or "pond scum", it's known to scientists as thallophytes and to water gardeners (who have stopped the name calling) as green algae.

Algae live just about anywhere you have light and water: in puddles, soil, even in your bathroom shower. It should come as no surprise that algae can grow like crazy in water gardens. Algae spores can enter your pond by wind, rain, on the sides of fish and on water plants you introduce into the pond. Single-celled green algae may form "pea soup" blooms, taking over your pond and overwhelming fish and submerged plants.

Green algae can not be totally wiped out from your pond -- nor should it. It's a natural part of the ecological food chain in all backyard ponds, maintaining "balance" and assisting in providing a vital environment for fish and other pond animals. So some algae is necessary. But here's another reason it's not a good idea to try to kill all your green algae -- it's an impossible task.

The reason? Backyard ponds have an unnaturally high ratio of fish and plants per gallon of water. While we may believe our water gardens are a "little bit of nature", they are very unnatural when it comes to biology and chemistry because of this imbalance of flora and fauna. This produces an ideal growing environment for green algae.

So what can a water gardener do to combat the 'green monster'?

1. Avoid too many fish in your water garden; more fish mean more poop which breaks down and provides nutrients like phosphates and nitrates for algae to eat.

2. Put a good number of aquatic plants in your pond. Aquatic plants soak up nutrients that otherwise would be eaten by algae. Cover half your pond with floating plants like water lilies, hyacinths and underwater plants like Cabomba.

3. Snails and tadpoles consume pond scum-type algae. Try a few Japanese trapdoor snails and tadpoles.

If these "natural" solutions don't seem to work, or you don't have enough time before your big backyard party, you can use an algaecide can be your answer. Bio-filters can also work; they're designed to take out harmful ammonia put out by fish, rotting plants and algae, and excess fish food.

Once again, the ideal way to get rid of excess algae in a natural way is to lower the amount of nitrates and phosphates in your water garden. You can accomplish this by limiting fish, their food and maximizing the number of water plants.




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