Saturday, 29 September 2012

The 'Green Monster': Green Algae in Your Backyard Pond

It's the scourge of backyard water gardeners everywhere: variously called "green water," "blanket weed" or "pond scum," it's known to scientists as thallophytes and to less-emotional water gardeners as green algae.

Green algae can grow in any environment where there is light and water: in mud puddles, dirt, even in your bathtub. It shouldn't shock you then that algae can virtually take over a water garden. Algae spores can come in your pond by wind, rain, or on fish and water plants you place into the pond. In extreme cases, algae can bloom into "pea soup," completely obscuring everything else, including fish and water plants.

Can algae be defeated by backyard gardeners? No - and it shouldn't be, at least not completely. That's because algae is an essential part of the natural food chain in all water gardens. Algae keeps the pond "in balance," helping to maintain a healthy environment for fish and other pond creatures. But there's another reason why you shouldn't try to eradicate green algae completely - it's impossible.

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.      Introduce lots of aquatic plants. Aquatic plants reduce algae growth by removing excess nutrients from the water. Try to cover 50% of pond surface with floating plants like water lilies and water hyacinths and submerged plants like Cabomba.

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

Sometimes all efforts of "natural" methods don't seem to work, or you've run out of time and patience. In that case, an algaecide can be your answer. Biological filtration can also help; it's designed to remove harmful ammonia released byfish, decomposing plants and algae, and uneaten 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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