Im kinda havin the same issues as you are so maybe we can work them out together, I have 6x1ooo watt HPS so we're @ the same wattage.
as for carbon filters, they need to be used properly to work properly. I dont think humidity affects it, but I know the speed that air flows through it does. pretty sure they are only supposedto be used @ 2/3 to 3/4 cappacity to get 100% of the odor absorbed.
does this help?