I think you have issues with your hydros, as this isn't a huge space you are dealing with. To have a 8% difference in that small of a space I don't think is possible when everything is working correctly or even incorrectly. I mean one set of beads could be really wet throwing out a lot of humidity, but if that is the case pull them out and let them dry out a little or vice versa for the other beads. Do you have leaks in the cooler somewhere, drain holes plugged, seal is sealing correctly? Seal around the fan assembly as maybe that doesn't seal 100%. These weren't built to hold humidity, they were built to hold temperature and whether they are good at it or not we don't know as they could just run more than they should to make up for shortcomings.