Having some algae in your pond or water feature is a good thing – but having pea soup clearly isn’t. Knowing what causes algal growth and how to minimise it will go a long way towards making the life of a pond owner stress-free.
Remember, like any plant, algae needs food and light in order to photosynthesise and grow and therefore to control it, a number of factors need to be considered. Excess algae is generally more of a problem in new ponds because the ecological balance between plant and animal life hasn’t yet been established and there are no natural predators which would normally keep algal growth under control.
It goes without saying that regular maintenance, monitoring and management of your pond is important for algae control but let’s look at the most common causes of algae problems and what can be done to minimise them.
High levels of light
Abundant sunlight accelerates the growth of algae, so when designing and building a pond, the long-term aim should be to starve algae of light. A dark colour on the pond’s interior is also important. Other things that reduce sunlight (and therefore reduce the ability of algae to thrive) include shade from nearby trees, shrubs and walls and of course, cover from aquatic plants.
High water temperatures
Again, good pond design (steep sides, deep water) will mean the larger volume of water will take longer to warm up, thereby slowing down the growth of algae. In other words, you need to maximise the pond’s volume relative to its surface area and remember, excess algae is more likely to be worse in the warmer months.
Pollutants in the pond water
Excess algae could also be caused by an excess of nutrients in the water. Check that run-off from your garden or lawn or even from rain which could contain soil particles, fertiliser or chemicals isn’t going into your pond and feeding the algae. It’s important to regularly remove excess leaves and decomposing organic debris from your pond in order to take away this source of nutrients for the algae.
Having the right types and amounts of plants in the pond is important, as these absorb nutrients for themselves and therefore starve the algae of its food source. A pond should have around two thirds of its surface covered by plants (e.g. water lilies) in order to reduce sunlight and lower the temperature of the water. Algae also feeds on fish waste and fish food, so it’s important not to overstock your pond.
Poor water circulation
Installing the right pond equipment is vital in order to minimise algae growth. Algae loves stagnant conditions, so it is important to keep the water moving with pond supplies like pumps and filters.
Chemical treatments can also be used to minimise algae, and the first step should be testing your water to identify deficiencies (e.g. wrong pH levels) and then getting the appropriate product to fix it. However, there are many different products on the market and it is important to discuss your needs with experts such as the team from Clearpond who specialise in creating, managing and enhancing aquatic environments.