Hi, had this problem ealier this year cos I installed a heater which -of course- encouraged all sorts of green stuff, go to a local pond or koi specialist shop there are dozens of treatments for all sorts of algae problems some of them colour the water for a few days but they do work as long as you get the dosage right, it worked for mine spectacularly. Hope this helpsalgae
Froggy_Bottom wrote: the water in my pond has become very green with a scum on the surface and there is string-like algae
I have to ask (Because you don't mention it) Have you not got a UV and biological filter?
The string like stuff is called string algae, there are various cures available the best one is a stck to remove it with, since what cure works for some one else may not work for you, but a stick works for everyone.
Can I just add to the removal of the string algae with a stick, just wind the algae around the stick to remove it from the water then leave the algae at the side of the pond to allow any creatures caught up in the algae to return to the water..if that makes sense