Well, two things come to mind... 1) You don't have to have your height the same as the footprint dimensions. I.e., maybe 24x24x20 or something like that. What height is your 20g right now? Or do you want to go to a higher tank anyhow. 2) If funds are an issue, maybe get the tank first, but budget for a light upgrade in the soon after. I'm sure the light would at least bridge you over the interim.
