So I just got a partial mash kit, it's pretty clear except one thing. I bring my wort up to about 160f for about 30-40 min with the grains in. When that's done I put the bag in a sieve and pour boiling water over (sparge?). My question is (instructions are a little confusing) do I keep the grain bag in during boil or is it done after the initial mash time?? I'm thinking it doesn't go in the boil but wanna make sure. Thanks