Posted: 20/05/2014 at 17:53
I think blanket weed and algae are both caused by excess nutrients (e.g. from fish/plant waste, soil getting in or using tap water to top up). Any plant you put in should in theory use up this nutrients then they won't be available to the blanket weed or algae. This year will be particularly bad because winter wasn't that cold so it hasn't been killed off.