Dealing With Algae in Your Wildlife Pond
It's that time of year when algae in wildlife ponds can start to be a problem. Warmer weather can lead to big problems. Algal bloom can turn it into a pea soup, and blanketweed spread across large areas.
Good or bad ecologically, they're not desperately attractive. Some are toxic and others reduce oxygen levels and hence water quality if they run amok. And they might.
Good and Bad Algae
For starters, let's make sure we're talking about the same thing. Algae aren't a type of pondweed and they're not duckweed.
There are good, bad and ugly algae. The green algae which seem to upset some people are actually beneficial. So too are Diatom algae, which annoy tropical fish enthusiasts. They may not be everyone's cup of tea visually, but they are oxygenators and typical of a balanced ecosystem.
Blue-green algae are by contrast highly unpleasant / toxic. Not so bad are filamentous algae, or Spirogyra, blanketweed. They won't kill potentially harm you, but they are unattractive and excessive growth will do your pond's ecosystem damage.
Head over to the British Phycological Society to find out more...
What Causes Excessive Algal Growth?
Algae are a fact of life for ponds. They'll arrive at some point; like Duckweed, on the feet of waterfowl, or via their wind born spores. They will get to multiply very quickly if conditions are right, however.
There are two factors responsible:
- Pond algae respond to sunlight and warmth. Sunlight drives more rapid growth, and warm water accelerates their metabolism. As springs and summers become hotter this problem will only get worse.
- Higher nutrient levels in water also promote growth - the phosphorus and nitrogen levels in tap water, for example.
There are various ways you can mitigate both these issues.
Solutions
There are a number of ways to mitigate algal problems, but no single solution.
- Bacterial controls, available commercially
- Remove fallen leaves etc., and/or net to prevent leaf fall
- Physically remove Blanketweed etc.
- UV Clarifiers
- Stop or divert nutrient rich run-off
- Use rainwater only to fill or top up the pond
- Plant aquatic plants - but don't use nutrient-rich soil
- Plant surface covering plants (lilies, Broad-leafed pondweed etc.)
- Create deeper water sections to reduce pond temperature
- Introduce Ramshorn snails, to eat decaying matter
- Add Barley straw in a mesh bag
- Add a pond dye
None of these methods are going to harm the wildlife in your pond - the opposite.*
Learn to Love the Look
My last point is really about a state of mind. Like a wildlife garden, a wildlife pond is never going to look beautifully manicured. Its manifest attractions are rather different. If there's a little blanketweed about learn to love it - just see how many invertebrates you can find in it!
*although take care if removing blanketweed and pond detritus...