should I keep it?
Eastern painted. Only keep it if you have a large tank to devote only to it; turtles are very messy, and so are their tanks. Largest ones I've seen wild were about 12" long. They most likely get at least 16".
I will not be able to provide him with a 75gallon tank, but I can put him in my parents pond. is that a good idea?
he is only 1.5" at the most now. should I just release him now or keep him in a smaller tank (10g) and set him free when he grows a little?