API's CO2Booster is a great product -- better that Seachem's Flourish Excel IMHO. NOw that you have so much light you need to add a lot of fast growing plants so algae doesn't over run the place. Get some stem plants -- rotala, ludwigia, hygrophilia difformis, etc and some Vals. You want your plants using the nutrients and the light, not the algae.
BTW, what size and what brand of T5HO did you get??