& Blanket Weed
in your Pond
Algae & Blanket Weed:
Blanket Weed is a form of
filamentous algae and in common with other pond algae occurs when there
is an imbalance in the pond ecosystem. This may occur in early
Spring as the temperature of your pond water starts to rise and before
the other plants in the pond have re-established after the Winter.
It will usually clear up within a few weeks. Or it may occur
with a newly constructed pond before a natural balance has been
Algae will always occur
naturally in ponds, but excessive growth can be detrimental. The
following factors will all affect the amount of algae present:
of sunlight penetrating the water,
of the water,
of oxygen in the water,
of nutrients present
number and variety of plants present
balance is needed between each of these factors to keep the amount of
algae in check.
For a healthy pond you will need
a balance of different pond plants
including oxygenators) and scavengers
(snails and tadpoles).
Increasing the number of pond plants will increase competition for
nutrients. Adding plants and floating plants will increase surface
shade and decrease the amount of sunlight available for the algae.
Oxygenating plants will increase the oxygen levels in your pond and
reduce the carbon dioxide levels – algae needs carbon dioxide to
survive. The increased oxygen levels will also be beneficial for
other pond organisms and snails; snails and tadpoles will actually eat
the algae and help keep the balance. Your pond should have at
least one gently sloping side to encourage frogs etc to breed in the
pond. Ensure that you don’t increase the amount of nutrients
introduced into your pond: ie avoid using tap water to fill the pond;
prevent run-off from lawns or garden borders into the pond (particularly
if fertilizers have been used); only use good quality aquatic compost in
your planting baskets.
If algae persists, then you need
to improve the balance of your pond. There are pond additives on
the market, but I wouldn’t recommend them as they will not help to
correct the basic imbalance in the long term.
Once you have taken
steps to improve the balance of your pond, you can help by removing as
much of the blanket weed as possible by twirling it around a stick.
Leave the blanket weed at the side of the pond for a while so that any
small pond creatures living in it can return to the pond. Barley
straw can also be used to inhibit the growth of algae while the pond
finds a natural balance – see our Pond
Pads which are made from barley straw and release natural
compounds which inhibit the growth of algae in the pond water for about
six months giving the pond a chance to establish a balance.