BIAB question

An authentic...Aussie-style BIAB does not have a sparge in its process.
An authentic...Aussie-style BIAB mash will yield the entire pre-boil volume.

A few more details about your process might help you get the help you need.

 

How big is your boiling kettle? I started brewing all-grain recently using a highly modified BIAB method (hell, all I have in common is I use a paint strainer bag). I only have a 5-gallon kettle and am making 2.5 to 3 gallon batches. I'll typically collect around a gallon and a half of wort from the mash, then dunk sparge in two 1.5 gallon shots, giving me a pre-boil volume around 4.5 gallons. Managing the initial boil is a challenge, but have not had a boil over mess yet; I have come very close. I'm getting about 80 - 84 percent efficiency on recipes up to 1.055 OG. Have not tried anything bigger yet.

Definitely NOT Aussie style, but it's working for me so far.

 

If you can help it always start with ~6.5 gal of wort at the beginning of the boil. This will help with hop utilization and your calculations for hops will be more accurate. Otherwise, the # of IBUs will be a touch low. If I were going to sparge I'd only mash with 1.25-1.5 quarts of water per pound of grain. I'd have a second kettle with the rest of my sparge water in it and dunk the grains in that one. I'd add the two worts together just before boiling. Sparging with 1 gal of water? Too little too late and it won't do much to get more sugar out. If you mash with most of your water in the kettle you may as well mash with all of you water in the kettle. It's a matter of preference, what you have available in gear, and how motivated you are to get more efficiency out of your grains.

Edit: You should have DME on hand so if you're low on your mark you can get up to the OG you want. Just remember this should be at a pre boil liquid level and a pre boil OG--not a post boil OG.

 

Here's a thread I started with BIAB questions. You may find it helpful. I certainly did.

This batch is slated for Sunday. I'll update it with results either Sunday night or Monday.

 

Here's a calculator for determining BIAB water volumes:
http://www.copycalc.com/bob/BIAB

I've done six BIABs, and I don't sparge. I brew 5 gal batches in a 15 gal kettle. After mash I drain the bag over the pot briefly, then drop it into an old kettle that has a collander upside down inside of it. I press down with an old kettle lid on the bag, and once I squeeze out some more wort I add it back to the brew kettle.