Originally Posted by mgortel
OK...here is where i get to learn something........how is mash efficiency different from total efficiency?
If I mash and get a SG.......how does it decrease by the time I end up after boil?
Well, yes, definitely. But there are a couple of different terms here to define first.
mash efficiency- how well you convert your starches to sugars. Should be very high.
Lautering efficiency- how well you get those converted sugars into the boil kettle in the liquid you've used. If you're leaving lots of sugars behind in the grain, this is where it would show- in the preboil SG.
Brewhouse efficiency- the actual % you get into the fermenter. This is with trub losses, kettle losses, etc.
If you are leaving, say, 1 gallon of wort behind in the kettle, your efficiency % will look low because you're not accounting for the gallon in the kettle. Some people do that, to filter out the hot break, hops debris, cold break, etc. But if you're going to do that, then it should be accounted for so that you hit your desired OG in the fermenter, although it's NOT part of the mash efficiency calculation.
I hope that makes sense.