I'm working on a pool in an area known for it's high iron content in the well water. The pool is filled with this well water and there is no option for another source. I have been dealing with this quite successfully by shocking, flocculanting and vacumming to waste. My question is this; why is the water green? I know it's not algae. I shocked the pool and then added more water.It turned jade green but not murky. I'm thinking copper (the largest copper mine in Europe is 30 miles away) due to the green colour. I also think the water is full of iron and manganese. The geology is schist.

Whats the color of the pool plaster/vinyl? Blue or slightly blue backgrounds will mix with the yellowish iron color and make the water look green.

Copper in the water plus shocking will turn the water a bright clear transparent emerald green. Iron plus shocking will turn the water clear transparent yellow, which often looks green when the pool surface is blue, not as bright a green as copper gives you.

Hi, thanks for your replies. The pool is tiled with beige glass mosaic tiles. I think this is over and above what you'd expect naturally. After what you said I'd guess it's a mixture of copper and Iron. I'll try and get some pictures but my cameraphone is well, a cameraphone.