Green Water Help?

[Grammie717]

ok so find the test kit for nitrate? We are going to be putting in a bigger filter system probably this weekend. Same setup but larger area...unless someone can give me a better idea on the filter system. Currently the water goes to bottom of of the filter can, with swirl piping setup, fills to the top and gravity falls to the water fall. One change will be that instead of the return to water fall being level the filter can will be slightly higher to that water is returning at a faster rate than it does currently.