Posted: 26/10/2012 at 23:47
Time is what is needed, time for the proper plants to get a hold and deal with the excess nutrients that is helping the algae to take a hold. Algae needs light, heat and nutrients (nitrate and phosphate) to grow. If your pond is less than say 2ft deep it will heat up quickly in the summer, which helps the algae take hold quicker than the beneficial plants. if there are not enough oxygenators in the pond, which help alongwith the ordinary plants, take out the excess nutrients in the pond, you'll need to add more, probably next spring now. A good marginal plant to have in the pond, is Typha Minima, as due to it being a Dwarf Reed, it will do the job that large reeds do in natural pond filters in house water purifification systems, but without the size problems these big plants bring. Light can be reduced by floating plants or the obvious Water Lilies and if possible aim to have a third to two thirds coverage. I've moved house a few times and one year I tried an experiment in a small pond I built. In the first year, I introduced Duck weed to give me really good cover while the lily was growing and for the 2/3 years I was there, I never had any blanketweed to speak of. Word of warning though, Duck weed is extremely invasive and after it had done it's 'job' I had to get rid of it and that meant every single leaf, which was quite a job I an tell you.
Blanketweed can be reduced to a manageable level quite quickly usual normal (already mentioned) ways, but that balance of plants can take months or in extreme cases, even years, but patience is all that is needed.
Hope this helps a bit, but whatever you do, try not to resort to chemicals, as it would only be a short term solution and will affect beneficial plants you want to do well.