hi,we had the same problem with blanket weed it can be hard to rid your pond of it,but we have managed it.Firstly if you can,is empty and keep as much as the water as you can,we used a pump and kids small swimming pool,then clean the sides with scratchy pads,then refill your pond with the original water and top up with tap water or if you have enough rainwater from butts even better.Then I treated it with a product called "no more blanket weed"this was the only product that worked for us,you will have to do it more than once and it's no good putting it in when there is waves of blanket weed this stuff is more as a preventive than a cure,probably take three goes but it will be worth it,you don't say if you have fish we have Koi,Tench and Rudd and it never bothered them,hope you pond isn't too big as it is not a cheap product