What you have
in your pond is called Blanket Weed. This is caused by
sunlight and compounds in your pond water called
nitrates.
There are
several different ways of reducing and getting rid of Blanket Weed
including natural, chemical and electrical methods:
Natural Solutions
Add Plants -
Blanket Weed feeds on the nitrates in your pond water and so by
adding more pond plants, which also feed on nitrates, you are
starving the Blanket Weed of food so it dies. This is the best
long term method but you need a lot of plants. If you are relying
on this method only then cover ½ to a 1/3 of the pond
surface in plants.
Use Bradshaws Get Rid of Blanket Weed - this
is an additive that works in four different ways to kill and remove
Blanket Weed. This is the easiest and cheapest way to control
Blanket Weed.
Electrical Equipment
Use an Electronic Blanket Weed controller -
this works best if you have hard water. The system works by putting
an electrical pulse into the water which disrupts the calcium ions
and causes the blanket weed cells to break down.
Bradshaws Direct (UK) - suppliers of pond liners (pvc and butyl liners), underlay, pond pumps, filters, pond vacuums, fish food, water features and many other water garden accessories.