If you have a swimming pool, algae is the last thing you ever want to see. That dreaded film of green coating the sides of your pool is enough to strike fear into the heart of even the bravest pool owner.
If you have a pond on the other hand, algae can actually be your friend – as long as you manage it properly.
What Is Algae?
Algae are related to fungi and bacteria. They are primitive plants which, although predominantly green in colour, don’t have any actual leaves. Nor do they have stems or root systems. Yet, despite these apparent limitations, algae have managed to survive over millions of years, adapting to changing and diverse habitats until the point where today, there are over 17 000 identified species.
In a pond, algae are usually the first plants to arrive after you’ve filled it up. They form the very foundation of the food chain and are critical to maintaining balance and productivity. Algae – which can be airborne, or arrive in your pond courtesy of birds that come to drink – will turn your pond green after only a few days, depending on the temperature. But this isn’t necessarily a bad thing. Fish are happy in green ponds as they can’t easily be seen by predators.
Algae oxygenate the water, and some serious koi enthusiasts actually make a point of keeping their fish in a green pond prior to showing them in a competition, as they find it makes the colours more vibrant.
So then why does algae have such a bad reputation?
One word – bloom.
An algal bloom is a sudden and rapid increase in the population of algae within a particular water system, such as your pond. Although the exact causes of blooms aren’t really understood, some can be the result of too many nutrients (especially nitrogen and phosphorus) in the water. Warmer weather and increased sunlight hare also thought to accelerate an algal bloom, which is why they are more common in the summer.
The problem with a bloom is that as more algae grows, other plants die. These dead plants then become food for bacteria. More food means more bacteria, bacteria use up the dissolved oxygen in the water, and without enough dissolved oxygen, many aquatic insects and fish in the pond can die.