Are green threads appearing on a stone, at the edge of the waterfall, or around a planting basket? These may be filamentous algae. The first steps are to observe their development, check the pond's operation, and carefully remove any bothersome clumps. A small tuft does not immediately justify intervening throughout the entire body of water.
Acting early is, above all, an opportunity to understand what is changing. Light, waste, feeding, and circulation can explain why filaments are becoming more visible in this spot at this time.
1. Verify that they are indeed filaments
Filamentous algae form threads, strands, or clumps that attach to surfaces and can then rise to the surface. Their appearance varies depending on the species and conditions.
Uniformly green water corresponds to a different type of problem. Small, freely floating leaves may be duckweed. An immersed plant has a structure that should not be pulled out by mistake.
Take a close-up photo and a general view before cleaning. If the material forms an unusual layer, has a suspicious color, or is accompanied by a strong odor, ask for advice before handling it. A photo helps guide the diagnosis but does not always allow for certain identification.
2. Observe the fish and circulation
Start with the pond's inhabitants. Is their behavior normal? Does their breathing appear normal? An isolated fish remaining at the surface and multiple fish suddenly coming up for air do not have the same significance as a clump of algae on a stone.
If the fish are in distress, immediately check the operation of the pond's circulation and aeration, then ask for appropriate advice. Do not add an anti-algae product before you have understood the urgency.
Next, check the strainers, the filter return, and the water flow areas. Filaments can accumulate on an intake and reduce the flow rate. Equipment checks or cleaning should be done after unplugging it and in accordance with the manual.
3. Note where the algae appear
The starting location provides clues. A very bright, shallow area may exhibit different growth than the rest of the pond. A stream, waterfall, or edge near a soil runoff deserves special observation.
Note recent changes: pruned tree, increased feeding, new fish, restarting filtration, or heavy rain. Visible appearance does not necessarily mean the problem stems from the last product used; you must view events as a whole.
Mark a few reference points on your photos. This will allow you to compare regrowth after the initial actions, rather than relying on a general impression.
4. Remove accessible clumps without stirring everything up
Once the identification is sufficiently clear, gently remove the masses that are bothering plants or circulation. Use a tool adapted to the access and the fragility of the supports. Avoid sudden movements against the liner.
Examine the clumps as you go: they may contain small animals or be mixed with useful plants. Work in sections and stop if you put a significant amount of silt into suspension.
Mechanical removal extracts material from the pond. To maintain this benefit, dispose of the waste in a place where runoff will not bring it back into the water. Do not scatter the fragments into another body of water.
A light presence on some surfaces can remain compatible with a living pond. The goal of the first pass is to clear what is causing a problem and to prepare for further observation.
5. Check useful parameters
Tests do not directly measure the amount of algae, but they help to verify water conditions. Depending on the context, one monitors pH, KH, GH, nitrites, ammonium, nitrates, or phosphates.
The JBL ProAquaTest CombiSet Pond offered at Aquishop includes pH, KH, GH, ammonium, nitrites, and phosphates. For nitrates, a separate test must be provided.
A low nutrient value is not enough to rule out significant input: the algae already present may have used up some of it. Cross-reference the figures with the photos, the food distributed, and the state of the bottom.
If you wish to have your water checked, consult the Aquiflor analysis service and ask for sampling instructions before your visit.
6. Correct what might be fueling regrowth
Observe a full feeding and spot the food that escapes the fish. Adjust the quantity to their needs and activity. Also check if their number or size has increased since the filtration was sized.
Remove leaves accumulated in accessible areas and prevent grass clippings from reaching the water. If every rain brings a trail of soil, work on the edges will be important for the future.
Plants can contribute to the pond's layout, but they must be chosen for their depth and growth habit. Adding many plants without adequate space may complicate maintenance rather than solve the problem.
7. Study Aquipond Greenstab if a supplement is useful
Aquipond Greenstab is offered to limit excessive algae proliferation. It should be considered after observation and testing, when the conditions of use match your pond.
Know the actual volume before calculating a quantity. Check the product label, required parameters, and other products that may be present. The word "natural" does not mean that the dosage or combinations can be improvised.
Keep a written record of applications and observations. A treatment does not replace removing a clogged strainer, managing feedings, or reducing external inputs.
What if silt deposits are also present?
Visible filaments and bottom silt are two elements to be examined separately. When organic deposits accumulate, Aquipond Bactovase can be studied for pond maintenance. It does not eliminate sand or soil.
A PondoVac 4 vacuum can allow for targeted removal on a suitable installation. Prepare for the working depth, access, and discharge of the vacuumed water. Do not vacuum the entire bottom without considering the fish, plants, and fauna present.
What UV and draining do not solve automatically
A UV clarifier acts on the water passing through it. It does not directly remove long algae attached to a stone or waterfall. Its proper operation can be useful for another problem, but it does not replace targeted actions on filaments.
Emptying the pond is not a necessary first reaction for a few clumps. Such an intervention is more disruptive to the installation and does not remove the causes fueling the algae. Prefer a diagnosis before considering heavy work.
The following days: watch the trend
Photograph the same areas and check the water flow. Look for concrete progress: less material to remove, plants that are clearer, or slower regrowth.
If the filaments continue to grow rapidly despite these actions, send the photos, your measurements, and the pond's history to support@aquiflor.com. The team will be able to help you choose additional tests and verify if an Aquipond product or a targeted intervention is relevant.
Sources
- Royal Horticultural Society — pond algae and blanket weed removal.
- Penn State Extension — identification and development factors of filamentous algae.
- Penn State Extension — preventing nutrient input.
- Aquipond — Greenstab ; Aquishop files for Bactovase, PondoVac, and JBL cited in the text.
