need homemade gumidor help please!

So I don't have much cash and just got into smoking cigars. I wanted a humidity but couldn't afford to buy a nice one so I made one. I used an airtight Tupperware box, battery operated hygrometer and tried a sponge and now am trying a gel filled tube. My problem ia I can't get the humidity level to stay between 68-72. It'd always between 77-81. I need help because I love the way it came out I just don't know what else to do do get the humidity right. I tried a smaller sponge, less damping of the along, then got rid of the along and tries the gel filled tube but still to much Social. Any ideas on how I can get this to work at the right level it what im doing wrong. Below are pics or links to pics so u can see what im working with. Please help! Thanks I. Advance.

My others pics are to large so if u think u can help I can email them to u or u can try these links:
http://i1134.photobucket.com/albums/...2-11-14_26.jpg

http://i1134.photobucket.com/albums/...2-10-48_75.jpg

http://i1134.photobucket.com/albums/...2-11-14_26.jpg