dont know if you have been told but running co2 that high when there that young will actually slow the growth wait till the last 2 weeks of veg and then run your co2 your just wasting it right now if you insist on using it i would run it @ 700-800ppm till i was 12" tall at least, i will say you have done a good job thus far and have sub as well can wait to see the end result, fyi your grow space and light are identical to a small ebb and flow grow i did and yeilded me 1.5lbs off a 9 clones with 7 day veg and 49 flower