Why is My Pond Foamy?

“My water is covered in foam! Did someone pour soap in my pond?”

Your normally beautiful pond has foam bubbles on the surface and you wonder if this is normal or if you have been hit by vandals. The answer is usually much closer to this being normal, but it is also something that should be addressed.
If you are seeing white foam on the pond surface most often this means that there is an excess of proteins in the water from dissolved organics. As the water is exposed to air such as at a waterfall it produces the foam. This foam is not harmful in and of itself, but is a sign that problems could exist. These dissolved organics that lead to the foam are a normal part of the biological process that takes place in a pond, but if they are not being broken down quickly enough then the foaming can occur. This unsightly foam is very common in the spring when the pond balance is not yet established for the season. Causes for an excess of organics include overfeeding, too many fish, inadequate filtration, inadequate aeration, an accumulation of leaves or other plant debris, or run-off making its way to the water.
Foam on pond
Now that we know many of the possible causes, what can be done? You can use a defoamer product to quickly reduce the foam, however this is not addressing the root cause.
Here are some steps to reduce the dissolved organic load:

1. Ensure adequate filtration.
2. Ensure fish load does not exceed the pond size and filtration.
3. Ensure that you are not overfeeding the fish. In one feeding, only give what your fish will eat in under 5 minutes. And limit number of feedings to fewer per day.
4. Use beneficial bacterial products such as Microbe Lift PL
5. Increase aeration.
6. Partial water changes to physically remove organics. Make sure a dechlorinator is used if on municipal water.

There is also another notable exception to causes of foam. The previous points assume that this is an issue that continues on a daily basis or is gradually increasing. A sudden or overnight appearance of heavy foam is frequently caused by fish spawning. This usually corrects itself in a day or two. Taking the above steps will still help ensure that all the extra proteins from this event are properly removed.