No, with two "one" inch turtles you should have them in at least a "20" gallon tank. Minimum tank size is Ten gallons per inch of turtle. A 1/2 gallon is TOO small by far. You need to read through the stickies here in the forum located at the top of each section and also read through the main site:
www.redearslider.com
There is a lot involved in owning a turtle let alone two and you must be prepared to give them the proper tank size with plenty of water and proper basking area, lighting (UVB bulb and UVA bulb), heater, filter, and diet.
First of all who ever sees this must return a pm to me, please. I just got two RES and they are about 1 1/2 -2 inches in length and I just wanted to know what to do with a few month old tutle. They seem to be okay eating turtle gammarus food but, i'm not so sure if the setting is okay for them. Is it okay to put them in a 1/2 gallon tank? I put one giant flat rock and other rocks off to one side for them to bask and i put water in the tank untill the edge of the rock so they can swim. They seem to like it but I don't want the slightest thing happening to them! I love so much! Please pm me. I need help! I am only a 13 year old!