Do your plants still look happy and healthy? If they do don't worry about it. All things being equal and one room has 30% humidity and the other room has the perfect humidity according to whatever that latest sabermetrics like humidity V quotient thingy is, the final results will not be that much different. The only thing that could be effected is yield. That won't be as much as you think either.
I could argue that I will sacrifice less yield for better potency. Because there is just as much if not more belief that in the outdoors plants that have hot, dry and under fertilized conditions have more resin to protect the plant. They look like crap sometimes but knock you on your ass.
It isn't worth the hassle to me to worry about perfect humidity. If you can correct it you should do so though because it will help. It helps with other things to. Mites don't like high humidity as much.
The bucket of bubbling water does help. You can increase the effect by making a towel rack over it. Take two bamboo stick or whatever and tape them on opposite sides of the bucket so they stick up about 2 feet. Then take another one and connect it across the tow on the sides making a towel rack. The fill the buck half way and take a small bath towel (pillow case works too) and dip it in the water and wring it out some. Then hang it over the top bamboo so it dips down into the bucket so it just touches near the bottom. Then fill the bucket to about 3 inches below the top.
make the sticks as tall as you need so the towel just gets near the bottom. The water is soaked up and evaporated from the towel and from the bubbles. It last longer than filling up a humidifier all the time and works enough to get a 4x4x8 closet 40-45% RH when without it mine won't even read the low RH of 20% my gauge reads.
I stopped even doing that anymore though. I keep my temps 78-80 lights on and 70 lights off. I also never let my pots dry out. That is the biggest thing. When I water I water them real good and I water them when they still have some dampness left. That helps more than anything. This keeps the roots moist and the mini atmosphere around each plant higher RH than you would read by measuring the room RH.
