Hi Indianajones,
I would look at keeping the light out of your bucket. I do this with thick black polyethene. Cut a hole in the middle of a sheet that covers your bucket lid about 1.5 inch in diameter then a slit from the hole to the edge so you can slip it over the plant. This will help prevent algae growth in your water.
Regards cain1.
PS I would not get to worked up over low humidity the plant will sill grow ok. Maybe plant will just drink bit more. Also look to lower res temps if possible.
Good tipp! I had a scary low humidity too in the first couple of weeks, didnt hurt my plants tho.