Pond Balance …. or, How to Prevent Green Water and Algae (yeah, right!)

A major concern of potential pond owners (and those who are new to the hobby!) can be summed up in one word - Algae! This is usually one of the first questions they ask.

What we tell people is that algae is usually caused by lack of pond coverage by plants and leaves (too much sunlight) or excess bio-load from too many fish, making the water just a bit too nutritious.

What we also tell people is that a little algae is good for you, and shows you have a healthy pond. A healthy pond comes from a healthy balance of all the elements of an ecosystem - plants, animals, insects, etc. Too much of any one element disrupts the balance, and another element tends to try to “take over” the environment.

That’s why too much sun is bad - plants need sunlight to grow, and they really do well if they get a lot of sun. The Sun also warms the water, and everything does better in warmer water. Plants also need food to grow (you fertilize your lilies, don’t you?), so fish fertilizer also helps them grow. Algae is a plant that is present in your pond, so it grows, too, only faster and thicker than anything else in the pond!

One day at a local garden center, I saw a water garden handout that brought a little more science and detail to the process of balancing a pond. Let me share some of the points they made here:

  • It takes time for the pond to “adjust” to the change of seasons, so algae tends to be a bit worse early-on;
  • Keep run-off water from getting in the pond. It carries silt, fertilizers and other chemicals that throw the pond off-balance;
  • If the pond is in full-sun, 50-70 percent of the pond surface should be covered by plants and leaves. Fewer plants are OK in a partially-shaded area;
  • Use one bunch (what’s a “bunch” equivalent to?) of oxygenators for each two square feet of pond surface. Use more for smaller ponds (I assume this is because smaller ponds warm up faster);
  • Use no more than one inch of fish per square foot of surface to begin with. (We like to see lots of fish swimming around, but fish excrement and leftover food feeds the “algae bloom” too). Don’t feed your fish more than what they can eat in about five minutes;
  • Add biological filtration. (This can be almost anything, from simple lava rock and polyester fill filter elements to the high-end charcoal filters with plastic balls with millions of square inches of surface area to breed bacteria. Take your pick!);
  • Keep dead organic matter out of your pond.

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