i have a small pond now (when i move so did my fish) i had a 2000ltr pond at the last house with no problem for three years but ive now got a 1000ltr plastic tank ( temp pond till new one built) im using a fishmate 5000 with 9volt uv and a oase aquamax 3500 pump but the pond is green? I have try green away (with uv off) still no good, tryed replaceing half the water, new uv lamp, cleanin every thing. Dont know wot to do now please help