Q: Why do I have foam on my pond?
Dom – Bellingham, WA
A: Foamy pond? No, the neighborhood kid (hopefully!) hasn’t dumped dish soap into your water garden or fish pond. The bubbly white or gray stuff you’re seeing on your pond’s surface is actually being caused by high levels of organic material in your pond. It’s natural – but it indicates an out-of-balance problem in your pond.
Question Your Water Quality
Foam forms when excess organic material has accumulated in your water garden. This happens when too many fish are living in the pond, you’re overfeeding them, you have inadequate filtration or there’s runoff flowing into the water.
When this nutrient-laden water pours down your waterfall, the air and water collide, causing the proteins and other organics to be trapped inside bubbles rather than turning into ammonia and nitrites. That air-water collision is why the foam seems to form at the base of your waterfall.
Tips for Removing Foam
So how do you get rid of the white frothy stuff? You can remove the foam in several different ways:
1. Use a defoaming product: A temporary solution is to dissolve the foam with a fish- and plant-safe defoamer, like Pond Logic® Defoam™. You simply shake the can and pour its contents into the water. The foam will disappear in no time.
2. Do a partial water change: To reduce the overall amount of organic material in your pond, you should drain the pond halfway or so and add fresh water and the defoamer. This will remove some of the organic material, dilute what remains and prevent foam from forming.
3. Reduce your fish population: Too many fish will produce excess waste, which means more foam. Remember that the rule is to allow 1 inch of adult fish per square foot of surface area – so if you have too many koi or goldfish in your pond, you might want to think about finding new homes for some of your finned friends.
4. Feed the right amount: If you’re feeding your fish too much, the excess food adds to the extra organic material in your pond’s water. Only feed your fish an amount they’ll gobble down in a few minutes.
5. Beef up your filtration system: A more powerful filtration system will remove those excess organics, so if you really want to erase foam, think about going bigger with your filter.
If you do suspect the neighborhood kids have dumped soap into your pond, your fish could be in danger. Do a water 90 percent water change before chasing the perpetrators down.
Pond Talk: Do you notice whether foam forms more often during certain times of year?