Do i need to vent when using leds and co2?

Im using 600 watts leds and a 20 lb tank with regulator on a timer i will let co2 reach 1500 than have it shut off for 3 hours than turn back on untill 1500. You think i will still need to exhuast through vents if im using co2?

u need a co2 controller to properly control the co2 level, not this 3hour bs..
and u dont exhaust if ur using co2, it all gets wasted straight outside, right.