so true both stoners & I was sick for few weeks, so i not remember much of anything... Okay 5x5 i'd say 3 bags, how many plants ya have? I wouldn't add all 3 at same time either 1 or 2, then 30-45 days out add 1-2 more just so always have high concentrations plus the little that gets removed by scrubber or leaks...you may want 4 total, start with 1 or 2 and just off set them by couple to few weeks each, to keep high co2 ppm inside room, try not keep open to often and let it all go out, make viewing window if possible...