pond/waterfall problems

Question
I have a small 2 tier waterfall and a pond at the bottom, about 4 feet in diameter and maybe 12" deep.  A pump recirculates the water with no filter.  It is located in my yard and receives a lot of sun.  My problem: algie quickly grows and the water quickly becomes a mirky green.  I have tried all sorts of chemicals that supposedly stop the algie but with no luck.  A gardner suggested hydrogen peroxide but that had no effect either.  What can I do to keep the water clean?

Answer
Hi,
I am sorry to say but I think your pond will allways suffer from blanket weed as you say it is in full sun and with it being small at 48"X12" deep the water will quickly warm up thus making the weed grow and the water turn green but if you have no fish in the pond there is chemicals that you can buy but if birds come to your pond for a drink out of the waterfall I would be wary of using chemicals the answer maybe make your pond larger and deeper.
George.