By Hoya105
Devon,
United Kingdom 
Does anyone know what this red algae stuff is? And if it is harmful or not? And what I can do to get rid of it if it is harmful? It turned up about 2 months ago and has got quite a lot bigger. The pond is topped up occasionally with rainwater.
22 Jun, 2013
I can't tell you what the specific alga is, but all I will say is that the other plants look ok, so I would add some more oxygenating weed (hornwort, curly pondweed) to starve out the alga. It's a surprisingly effective measure (and the ecologically sound way).
22 Jun, 2013