A few questions on my golden APPLE SNAIL!?

Well, i brought a golden apple snail 2 days ago ,it lives in a 22 litre tank in tapwater that has been treated with tetra's 'aquasafe' (makes tapwater safe for fish) and the water is just below room temperature (21 degrees centigrade).i feed him algea wafers and fish food flakes.how long do you think he will live and is this temperatur ok?