Hello Tuffy,
I see you are from Wales in the UK.
We call blanketweed 'string algae' on the other side of the pond.
This product is something that I don't think we have in the US. I looked it up
on Google and found this description:
Blanketweed control -- Electronically, using the Blagdon Blanketweed
Controller. This is fitted to the pipe on the way to the filter and disrupts
the calcium ions in the water causing the blanket weed to stop growing.

I have heard of fooling around with the calcium needs of string algae to
distrupt its growing.

If you can't find an answer from one of our UK posters and have tried
uk.rec.gardening I would suggest contacting the company directly and see what
they have to say.

And you can read the rec.ponds primer on overall algae control link in my sig
below (a collection of tips from rec.ponders gathered over the years).


kathy :-)
algae primer
http://hometown.aol.com/ka30p/myhomepage/garden.html