I am having a hell of a time meeting my target OG. I think it is because I am using too much water. Is there any real benefit to sparging twice vs once. Shouldn't I just measure how much wort I need after my original mash and sparge once with that? I am using 1.25q/lb of mash water originally.
Thanks.
A couple of things to check on before you move on to batch sparging as the issue.
First, for your mash, as others noted, check the grain and be sure that it has been ground correctly. You might have to crack those grains a little more. That almost always improves efficiency, but also increases a chance for stuck sparges. I crush my own an by LHBS, and usually set for .035.
Second, check the PH of your mash/sparge water. You would be surprised at how this may affect your results. I was using city water, but did not realize I had a PH of over 7. I switched to filtered store water (the kind you refill for .30 cents a gallon at the local grocery store), and that has a PH of about 5.3. My efficiencies shot up about 5 to 10 points. I do add Gypsum usually, but that is about it.
Third, and I apologize if this seems redundant, but do ensure that you are hitting your mash temps and stirring quite well the grains that you are adding to the strike water. If you are not checking the temp after 5 minutes of the mash sitting, you may actually have a mash temp that is much different than you thought. Also, ensure that the grain is thouroughly stirred up. You may be doing these already, but if not, it is a good place to look into.
Mash for 75 - 90 minutes. This helps ensure full conversion, and there typically is no bad results from doing this. It is not always needed, but it sure does not hurt.
Your 1.25/qts per pound is a great medium, so that should work well for almost all beer styles.
So.... if all the above are working, single or double batch sparging should typically give you very similar results. The main reason to go double (or even triple) batch sparging over single is ML space: a brewer may not have the ML space to account for all pre-boil volumes.
Really, batch sparging is quite simple. Assuming a single batch sparge (if you have the space), add your sparge water at the correct temp. Here is the part that you might be missing:
Stir the strike water/mash, and let sit for 5 minutes. Drain the second runnings at a moderate pace, vorlouf the first couple of quarts till clear.
Using these methods, I have hit target OG's or been within .001/2 or so for about the last 12 batches.
I hope this helps in some way.
Cheers,
Broc