I have a 270l heavily planted tank with fish and RCS. I have 2 x 42" t8 tubes ( one for plant spectrum and one for fish colours). My specs are temp 27C, Ph 7.2, ammonia 0, nitrite 0, nitrate 5, Kh 6, Gh 6. I use standard dose of excel every morning. I use co2 injection for 10 hrs to attain 15ppm...