Advice - algae & blanketweed control

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To achieve blanketweed control you need to understand it.

Types of algae growth:

  • Blanketweed is one form of algae.
  • A second algae form appears as a green scum or layer of froth on the water surface.
  • A pea-soup coloured pond or one containing blanketweed (or filamentous green algae which looks like green cotton wool in the water) are both thriving on surplus nutrients and mineral salts in your pond water.
  • They especially use nitrates and phosphates.
  • Remember - if the algae is the only plant form in your pond then that is the one that will grow. It will thrive on all the available light, warm and food sources available.
  • As the water warms up it grows even quicker.
  • Algae growth in Spring outstrips the growth of natural predators like water fleas and many pond plants.

Algae growth:

  • New ponds often have early season problems with pea-soup algae but this is due to an imbalance between the nutrients in the water and the amount of plant growth.
  • This algae has no fibres to it but the microscopic cells will stain your fingers if you drag them in the water.
  • This will normally settle down as the water matures but may take a full year to do so.
  • Speed this process with Cloudy Water Treatment

 Blanketweed growth:

  • Blanketweed is fibrous and spreads across the pond surface as a thick blanket made of many strands or filaments of plant growth.
  • In the short term you can remove excess blanketweed by twisting it on a stick or rake but you need to open out the twists to release any creatures and leave on the pond edge.
  • Later remove the debris from the pond edge so that the nutrients in the blanketweed do not leach back to the pond and start the process again.

Algae and blanketweed control:

To control the growth of any algae you need to remove the conditions that it enjoys:

  1. shade the water so it remains cooler,
  2. remove surplus nutrients by adding plant growth to act as competition for the free nutrients,
  3. control the amount of rotting vegetation in the base of the pond that releases surplus nutrients,
  4. reduce overfeeding of fish that allows surplus to fall to pond base,
  5. reduce stock levels of fish as they create too many nutrient high waste products in the water

Prevention of algae growth using plants:

Prevention is better than cure:

  • Add the right quantity of submerged oxygenating plant growth to use up the ponds nutrients. One third of the volume of your pond water should contain healthy, submerged oxygenating plants.
  • Cover half to two thirds of the pond surface area with floating leaved plants (either waterlilies, rafting plants or floating plants). Give shade across the surface to keep the water cool.
  • Keep the water moving as some algae forms prefer still water so pump systems can help.
  • Attach the pump to a biological filter to remove nutrients with a UV light system to break down algae strands.

Sludge layer:

  • A thick layer of sediment sludge on the bottom of the pond will release nutrient. A bit like the nutrient levels released by compost from your compost heap when added to the vegetable patch.
  • Treat this foul smelling sludge on the pond base using Mud Muncher on a regular basis.
  • Remove any excess sediment in Autumn maintenance.

Blanketweed control using Barleystraw:

As a further aid to preventing algae use a barleystraw product that suits your pond size:

  • Barley Bio Algae Control for a small pond or container -
  • If you have been treating pond algae with Barley Bio and it's fighting back in hot weather, increase dosing frequency, not the dose size
  • Barleystraw minibales for a larger volume of water -
    Each bale will float on the surface of the pond where the oxygen levels are higher and this increases the effectiveness of the straw.
  • Barley minibales are most effective when placed in running water - near a waterfall, pump or filter box outlet.
  • all are organic inhibitors to the production of algae growth.

Recommended products and plants: