lol i never bother with humidity, as long as you dont go bringing in alot of water and boiling it up in the room or anything, youll be fine, most rooms are dry enough, its larger scale grows that really get humid as orangeman said its probably low nitrogen, try going back to the first nutes you were using, and if it helps, use it for the rest of its life, also just wondering, you got much perlite in there? personally ive never had this problem, any leaves that went yellow for me went yellow in patches, so i think this is a case of low nutes, like i say, try using the old nutes, that might do the trick, peace and good luck. - expect me back sometime soon - i like this thread