Pond & Lake Q & A
Q: How do I control floating and bottom-growing algae in my lake? – Tom in New York
A: Whether it’s floating or submerged, algae can turn a lake into a green mess in no time. It’s unsightly, it’s sometimes stinky and in extreme cases, it can cause a fish kill. The good news is that algae can be controlled no matter what time of year. It starts with controlling the population and ends with a long-term management plan.
Before we dive in, it’s important to understand the difference between algae and weeds. The term “algae” refers to a wide range of single and multi-celled organisms that live in the water and metabolize carbon dioxide into oxygen via photosynthesis, just like plants. They differ from plants or weeds in that they don’t have true leaves, roots or stems.
In lakes and ponds, the most common varieties of algae include: Green floating algae that creates a “pea soup” appearance; Chara or Stonewort, which are a bottom-growing, seaweed-looking type that can be mistaken for weeds, and string or filamentous algae, which are actually long strings of algae connected together.
Sometimes, pond and lake owners may mistake duckweed for floating algae, but if you look very closely, you’ll find that it’s actually duckweed or watermeal. Check out this blog entry to learn more about controlling this invasive weed.
If your pond is coated in pea soup or the bottom is carpeted in Chara or string algae, you can knock back the population with a chemical herbicide like Algae Defense® . It provides quick results and it’s formulated to get a pond under control – especially during the hot summer months. Do not use if your pond or lake is stocked with koi or goldfish. If your pond has trout, check your carbonate hardness with a water hardness test kit, like the Laguna Quick Dip Multi-Test Strips, and make sure the carbonate hardness is above 50 parts per million (ppm) before using Algae Defense®.
Algae Defense® by Pond Logic® will solve a crisis, but to keep your pond or lake looking clean and clear, you’ll need to be proactive and develop a plan to manage the algae. The most successful approach centers on cutting off the algae’s food supply – nutrients.
Nutrients can come from a wide variety of sources, like grass clippings, twigs, trees, fish waste, yard and farm fertilizers and runoff. As these nutrients break down, they produce ammonia, which triggers the nitrogen cycle. Nitrifying bacteria surround the ammonia, turning it into nitrites and then into nitrates (nutrients) – which then feed the algae.
So, how do you reduce the nutrients in your pond?
Try these tips:
- Buffer before fertilizing: To prevent inadvertently fertilizing the algae, leave a buffer area around the pond. You can also try using organic or low-phosphorus fertilizers.
- Aerate, aerate, aerate: Because that muck at the bottom of the pond feeds the algae, you should prevent the buildup with proper aeration.
- Reduce the muck: Use natural bacteria like MuckAway™ by Pond Logic® to breakdown up to 5-inches of organic muck per year. You can also rake your pond using a Pond & Beach Rake to remove dead vegetation, leaves and other organics that will eventually decompose on the bottom.
- Reduce sunlight: Like all photosynthetic organisms, algae requires sunlight to thrive. Adding pond dye can help provide shade. If possible, consider adding some non-invasive aquatic plants to your pond. The plants, which also consume nitrates, will also be a source of competition for food.
- Add beneficial bacteria: You may also consider adding some additional beneficial bacteria, like PondClear™ by Pond Logic®, to your pond or lake. The bacteria gobble through nitrates, breaking down fish waste, leaves and other organics that accumulate in the pond, naturally improving the water clarity.
That green gunk can be controlled in your pond or lake. It just takes a little planning and some proactive management. When you see the results, it’ll be worth it!
POND TALK: When was your worst algae bloom and how did you control it?
Filed under: Algae Control, Algae Defense, Carbonate Hardness, Chara (Algae), Duckweed, Emergent Weeds, Fish Kill, Goldfish, Koi, Muck, MuckAway, Pond & Lake, Pond Clear, Pondweeds, Watermeal Tagged: | algae, Algae Control, algae defense, chara, controlling duckweed, fish kill, muck, muckaway, Pond Clear, PondClear, Watermeal