When you have a problematic pond that is full of algae there are two approaches; reactive management (covered in “Too Much Algae”, page 4) and preventative maintenance. Preventing algae growth means eliminating one of the factors that helps it thrive. These factors are light, nutrients (food) and carbon dioxide. We will look at each of these individually and how they can be effective at preventing your pond from being over run.
Firstly, access to light is essential for algae and all plants, they need it to grow and thrive. Reducing the amount of light that reaches the bottom of your pond can reduce algae growth. This is especially effective with filamentous algae that generally grows in stringy mats that start at the bottom then break off and float to the surface. The most prevalent way to reduce light penetration in a pond is by using pond dye. Pond dye effectively reflects light off the surface of the pond and so prevents it from reaching the bottom. It is most effective in areas that are deeper than 6’ so you will likely still have growth around the edge of the pond. Pond dye has another advantage of being extremely safe to use as it is a non-toxic vegetable-based product that does not harm any wildlife or pets.
Another approach which can be used alongside pond dye or independently is reducing nutrients in the pond. Nutrients such as nitrates, nitrites, ammonia and phosphate are all food that algae needs to grow. Since algae does not have roots it absorbs its food directly from the water. A probiotic can be used to intercept the nutrients that are dissolved in the water before the algae have a chance to use them up. This approach is effective against both filamentous and planktonic algae, although we often use different products depending on which of these two you struggle with most. Products like Water Column Clarifier are particularly helpful with planktonic algae, which often appears as murky green water, as it not only uses up the nutrients in the water but also helps to clump together any dead algae to settle it down to the bottom.
The third factor that algae and in fact all plants need to thrive is carbon dioxide. To reduce carbon dioxide in the pond we suggest using aeration. This will replace the carbon dioxide in the water with oxygen. Oxygen is not only not helpful to algae growth but greatly accelerates the break down of nutrients in the water as well. We will review aeration options and how to find the right one for your pond on page 14, “Choosing the Right Aeration for You”.
These three approaches can be used independently or together for maximum effect. You can also pair these with the reactive treatment discussed in the previous article to prevent the algae from simply regrowing after you get rid of it.
We would be happy to discuss these approaches, and which may be the right fit for you. We also offer water test to help you determine if you have high soluble nutrients in your water that may be causing algae growth.
