More important than temp is pH. Many people steep the grains in as much water as they can, resulting in a high pH. The grains have a natural tendency to pull the pH down, but if you steep in too much water the grain doesn’t have enough buffering power to do that. For best results, use about the same amount of water as you would if you were mashing. 1.5-2 qt. of water per lb. of grain works great.