Way too small, even if it is a breeder tank. The rule of thumb is 10 gallons per inch of shell, cumulative, although I prefer 15 gallons per inch when there are any aggressive, territorial turtles, such as sliders. Depending on the subspecies of painted turtle, you are looking at a combined shell length topping out at up to about 16". You could put two hatchlings in the tank but would have to start hunting for another tank immediately. Wading pools are probably the cheapest option.