today my girls are beggining there eight week at the beggining of the seventh week, i changed the light over to a red hps, i have changed her back after about a week then gone back to my blue mh also ive noticed that my girls leaves the ones on the top 2 branches but not in the middle have started to get browning on the tips and the under leaves r looking a bit grim but apart from that she looks fine, i have noticed that her humidity might not be wat she wants (35-40) and not even 40 till she`s turned off. like i say it seems to be low i have two small fans inside the tent and another in one of the top vents sucking out the air, i have been trying to create some co2 as well by using bicarbonate of soda, and baking yeast, in the uk it is hard to find a shop that actually sells normal yeast for brewing, in america they seem to have no problem with all that! i have also tryed to search for dry ice but to no avail, ! ny suggestions on co2 canister`s? 