check nick's nursery on chambers/aurora..these guys in the last two years have put in the back of the store a complete hydro/organic grow section with lights,fans,nutes,buckets,tents etc etc..it has been my go to place for a long time now and only now am i starting to tell peeeps about it. i think i saw big white sq/pots there but not sure on size i think 2-3gl :rasta:
or try
big tomato
aurorahydro
or HTG in commerce city