tank upgrades.

[mr funktastic]

i am building a 4 x 24" light hood for my 20 gallon tank this weekend. i will have 2 lights on each switch so i can switch between alot of light and a little light for like noon effect or something. i was also thinking of having them on timers so the 2 lights go on at 9am till 11pm(kinda long i know but that it what i have always done) the second set comes on from 11am till 2 or 3pm. i also just bought some excell a few days ago. it says to dose 1 cap for 20 gallons twice a week. can i do more than that? i have hagen co2 system on there and am very happy with the results i have gotten so far. is there anything else i should be thinking about doing? with the 4 lights (t-8 bulbs) i will be hitting 3 watts per gallon becasue they are 20 watts a peice. this will allow me to grow pretty much anything right? even if it doesnt grow fast. thanks in advance.
ps this is directed at travis simonson i was wondering if u were still up to sending me some plants and i think u will be able to send a differetn range of plants with my new lights.