With the arrival of spring and summer, that once clear and picture perfect pond is now turning a soupy shade of green. It makes viewing fish nearly impossible and takes a lot of fun out of owning a pond or water garden.
It's a common problem for a lot of pond owners.
What your looking at is actually very small, near microscopic size plants called algae. When all of these little critters group together and get so dense they can literally shade the water and turn it into what appears to be a solid green mass.
Now let's be clear on this. We're not talking about a light tint of green in the water, which is actually a really good sign. We're talking about water that is so green that you can not see an inch or two under the surface!
For the most part, the biggest problem with planktonic algae is really the view and the disappointment of the pond owner. Fish generally can tolerate green water ok, although even they have limits.
The good news is, that even though green water can be a challenge to treat, there are options and solutions. Since what we're really dealing with his is algae … we want to take a standard approach to dealing with any algae problem.
First of all, be sure to try to identify the support or nutrient source that is supporting this algae growth. Do you have too many fish in the pond for it's size? A good rule of thumb for this is 1 inch of fish for every 10 gallons of water in the pond. Any more than this and you might be overstocked.
When fish are overstocked, they produce more waste material than plants and naturally occurring bacteria can keep up with. When this happens, there is a large excess of nutrients in the water which fosters aggressive plant growth … like algae.
Nutrients can also come from decaying matter that may fall into or lie at the bottom of the pond. Like a compost pile for your garden, this deciding matter simply adds more nutrients into the water, which is something you do not want or need if you already have algae.
Finally, be sure to check for run off into the pond. Most homeowners work really hard to make their lawns and landscapes look really nice. If your adding fertilizer to your lawn or anywhere around the pond, there's a good chance that some of it can runoff into the water …. thereby adding more nutrients to the water.
So, your first objective to combat green water is to try and reduce these nutrient impacts.
If you do that and still have an algae problem, the next thing to consider is adding a benefical bacteria and enzyme product to the pond, or adding more plants to help control or balance out some of the nutrients. In most cases, using one or the other, or a combination of both will help quite a bit.
And here's a final word for caution. If you have fish in the pond, I'd rather advise against using any type of algaecide product. It's very hard to treat green water with an algaecide in my opinion without doing some harm to fish. Many pond owners have written to experess their dismay of misapplying a copper based aglaecide and losing all of their fish in a very short time.
Try the natural and progressive options first and if need be, contact a local pond professional to help get your pond back into balance in the safest way possible.