Using a water softener (low GH, high KH)?? Don't worry too much about the phosphate right now - it won't kill the fish. Worry about the nitrite - where is it coming from? My thought is you might not have enough plants in there, so the nitrite is the result of the nitrogen cycle establishing itself - if so, keep up the water changes and wait it out.KH: 107.4 ppm
Phosphate 10ppm !
Also check your source (tap and/or softened) water - could the phosphate, nitrite, and nitrate come from there?