Leopard Gecko Tank Help?

Ok so i am thinking of getting a leopard gecko, i already have a 10 gallon tank to put it in; but the problem is that the 10 gallon thank i have used to be used for fish, when my fish died i took it out and drained the water, but since then i haven't cleaned it, if i cleaned it properly and disinfected it a gave it a good clean would it be alright or would bad bacteria still be there that could harm the Gecko? I would get a new thank but im thinking abut cost. Please reply i really need to know, Thanks.