The Problem
Unless your water feature is foaming like a bubble bath due to a prank or accidental spillage of soap, there's no need to panic if you spot foam formation on your pond. True, the sight may not be too pleasing to bear, but one thing is for sure.
Why Pond Foam Forms?
Spawning Season
There are a few reasons why pond foam forms and some of them are definitely not a cause for concern. For instance, if you find pond foam accumulation right about dusk or daybreak during spring time, you shouldn't be concerned. In fact, you probably should be rejoicing! Fish, like most animals, mate in spring and typically do it at dusk or daybreak. So this exciting activity would explain pond foam sighting at that period. The foam you see could also actually be fish sperm and eggs released when spawning.
Protein Skimming
A pond has its way of naturally trapping proteins and other organics wherever air and water collide. This end up as ammonia and nitrates in bubbles and can be typically observed at the base of a waterfall. If bubbles mainly just accumulate at the base of the waterfall, your pond is most probably just skimming proteins from the water.
Stressed Fish
Stressed fish produce slime, which is organic and can possibly be a contributing factor to pond foam. If this is the case, check for causes of stress like ammonia levels, nitrite levels and pH. It would also be clever to have a vet take a slime sample to rule out parasite-caused diseases.
Excessive Algae Growth
The wide-spread growth of algae can induce the formation of pond foam. This is because an over-population of single celled algae releases abundant organic compounds that result to foam.
Use of Pond Medication and Additives
Some pond medication and additives, especially those containing vitamin complexes are capable of making water foam.
High DOC Content
Accumulation of dissolved organic compounds or DOC in the water over time encourages stable bubbles to form. End products of digestion from the metabolism of fish and other aquatic life make up a big percentage of DOC build-up in the water. Expect higher DOC if fish are fed with high protein diets. When leached into the water, formation of pond foam occurs.
The Threat of Pond Foam
As mentioned before, pond foam sighting may not pose an immediate life-threat to fish, but it could be a sign of water issues that can harm your fish in the long run. So once you have ruled out spawning and other natural causes of foaming, further investigation is recommended. That's because if the cause of your pond's bubbling is DOC accumulation, this could potentially lead to harmful oxygen depletion and toxic by-products (i.e. ammonia) build up.
Oxygen Depletion
For oxygen to be available in your system, it has to be first dissolved in the water. Water can only hold a limited amount of solutes dissolved in it. This means that if your pond water is already loaded with dissolved organic compounds (DOC), then the amount of dissolved oxygen it can hold is reduced. This could be dangerous for fish and other oxygen-requiring organisms in your pond.
Secondly, DOC is a magnet for bacterial activity that results to greater consumption of oxygen in your system. A continuous increase in oxygen demand by an increasing population of DOC eating bacteria may eventually lead to life-threateningly low oxygen levels for your fish.
Preventing Oxygen Problem with Simple Anti-foaming Tips
If you suspect soluble organic compounds accumulation as the culprit for the appearance of pond foam, regular partial water changes would help solve the problem. A water change dilutes organic-laden old pond water with relatively purer water, which helps stop problems brought about by high DOC levels, including oxygen depletion and foaming.
Knowing that a lot of organic compounds get to the pond through fish food, another way of addressing this problem is by trying different diets until you find the best one that produces less bubbling effect to your pond.
The Solution
Use Hydra Aqua Pond Defoamer to safely and effectively remove foam accumulation until the actual problem is rectified.