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.
Green algae can flourish wherever there is light and fresh water — in puddles, holes, even in your bathroom. It shouldn’t surprise you then that green algae can overwhelm a typical backyard pond. Spores can invade via wind, rain or on the backs of fish and plants you buy. In the worst case scenario, algae can bloom into something called “pea soup,” completely hiding everything else, including all your fish and underwater plants.
Green algae can not be completely eradicated from your pond — and it shouldn’t. Algae is a vital part of the natural ecology in all backyard ponds, keeping it in “balance” and helping to maintain a healthy environment for fish and other pond creatures. So a little algae is a good thing. But there’s another reason why it’s not sensible to to wipe algae out completely – it’s simply not possible.
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. Don’t put too many fish in the pond. More fish means more waste released into the water. As fish waste breaks down, it releases nutrients like phosphates and nitrates for algae to feast upon.
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 algae. Introduce some 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.
To sum up, the optimal way to curtail algae naturally is to minimize the amount of nitrates and phosphates in the pond. You can do that by lowering the number of fish, lowering their food supply, and increasing the number of aquatic plants.
Author: Keith KlamerThis author has published 3 articles so far.