stick with the 12g tank. if you get the 5 you wont be as happy as you would with the 12. if its a matter of money just save up. until you can get everything all in order. like i had all my filters, substrate, heater, light, msc stuff. before i even bought a tank. but that was how i was doing things. i had my stand built before i had the tank. stick with the 12g you wont regret it.