Will my Glass 20 gallon be safe for a hamster?

I highly recommend glass tanks for hamsters since they will chew through plastic ones. The windex should be fine by then, but if you want to be sure, before putting it to use, dilute it with water. Glass tanks work best for small pets such as hamsters and gerbils so they dont throw bedding out or chew through the plastic. make sure you have a lid though so it wont climb out if you have any tall toys or houses for them. Good luck :)