Goop bought a sachet 265 lt holding tank 2 lemon barbs two weeks , added another filter another week , set up 600 lt tank added barbs both filters & one extra ordered another sachet of goop to both extra filters, later 2 silver dollars & severum , running a week , this is just build up to me getting my Fly River turtle, added him yesterday , fish breathing heavy , water test nitrite 2.0 nitrate 40.0 , just done 50% water change , don’t bother buying it , might as well chucked fish straight in , my tank downstairs 0 nitrite always?