If BeerSmith says that my strike water temp should be 155 degrees, I put the prescribed amount of water in but add 10 or 15 degrees, so 170 degree water in this example. I then put the lid on the tun and swish the water around for a few minutes. Then I take the top off. When the temp settles to 155, I stir in the malt. Since the mash tun has been preheated, I come really close to hitting my strike temperature this way.