Pond algae is unsightly and may be detrimental to the health of the pond. Too much algae can clog filters and choke out plants. Microscopic floating algae is beneficial in small amounts, but large amounts of this planktonic algae, in addition to blanket and string algae, have to be controlled for the benefit of the pond ecosystem. If the pond comprises chemical, fish algae control might not be an alternative. There are non-chemical approaches to keep algae from the pond that won’t harm plants or fish. When the algae is under control, a couple of maintenance changes will help keep away the algae.
Remove the plants and fish from the pond and set them in temporary home if the pond is small enough for this to be achievable. Drain the water from the pond until the bottom and sides are exposed.
Coat the algae-covered regions with a non-iodized salt. Wait three days to get the salt to dry up the algae. Scrub the dried algae from the sides of the pond, the filtration system, water features, and some other rocks or decorations at the pond. Rinse out the pond before the algae is gone. Refill the pond.
Skim the debris from the pond surface and use a pond vacuum or net to remove the debris from the base of the pond if draining is not an alternative. Eliminate as much of the debris as possible to remove the algae’s nutrient resource.
Add barley straw to the pond to control algae. Use .025 pounds of straw per square yard of surface area. Put the straw in a mesh bag with a rock for weight. Put the bag in the pond and let it sink to the bottom. As the straw decomposes, it releases a chemical that controls algae. It works best if added in the spring before the algae gets overwhelming.
Install air diffusers to circulate the pond water. Algae forms in stagnant water that has stratified so there is less oxygen at the base of the pond. Keeping the water moving leaves the environment less habitable for algae.
Reduce fish feeding. Only give fish sufficient food they can eat in five minutes. If fish are overfed, the nutrients that feed the algae development are found in much higher proportions at the pond.
Maintain a skimmer handy. Remove debris that falls on the pond surface before it sinks to the bottom of the pond to decompose. Depriving the algae of this extra nutrients keeps it from growing.
Add plants both in and around the pond. Aquatic plants will compete with the algae for nutrients. They also add more shade to the pond. Small plants, trees or shrubs planted near the pond will add some extra attention to this pond area, and will provide more shade to the water. Algae needs sunlight to grow. The less sunlight available, the less algae there’ll be.