ok here it goes. height is more important than length for a crested gecko. u can use a 20 but a tall tank works better cuz they are climbers. i use an exo terra for my big one and my lil one is still in a kritter keeper. baby food is no longer an accepted form of diet and my geckos dont get any at all. everyone uses a form of crested gecko diet and dusted crickets dubias. i use repashy 3.0 and they love it. its relatively inexpensive and an 8 ounce bag lasted me 7 months.

i use paper towels for substrate but coco fiber also works excellent. i change thier food every 2 days and feed crickets once every 2 weeks. no lighting is necessary but i keep my tanks at 75 degrees. nothing over 80 in my opinion. keep humidity up and remember they are more active at nite. i can handle mine for a while but thats cuz he is used to me. most ppl agree that 30 minutes at a time is about as much as they like to handle without being too stressed.

keep in mind that crested geckos drop thier tails and it doesnt necessarily mean its a bad sign. my gecko was purchased tailless and he turned out to be an awesome pet. good luck i hope this helped