My personal opinon is to get the dehyrdated water crystals from pro geckos, i have been using them for some time a 1oz bag will last a long time, you can either get large or small crystals. Send cody an e-mail i'm sure he'lll be more then happy to help out
I just recently purchased 1lb. from Cody. It was a GREAT price, and he's a pleasure to do buisness with, I'd deffinatly take a look at his web site (Pro Geckos- link is at the top of the page under site sponsors)