Question on my 2nd biab

[RichardM]

On my 1st biab brew I went with a Munich Dunkel. The recipe called for a 60min 155deg mash. Being my 1st and not how my efficiency would be, I mashed in 5gal of water with 1/4 campden tab predisolved. At the end of the mash I hung the bag and heated the water. When the bag quit dripping I poured room temp filtered water over the grains until it got to 6 1/2 gallons. I did not check the preboil gravity, but ended up overshooting the Og a little. The target was 1054 and I was at 1070.

My 2nd is going to be a bock. It calls for a 90min mash at 152 in 3ga of water, then sparge with 3 3/4 ga of 168deg water. Should I just mash in 6 3/4 gal? Is doing less and then topping up to preboil volume over the grains like I did before a good thing? Also does it really need a full 90min mash?

Thanks

 

[IslandLizard]

BIAB is typically done with full volume, or with some water left behind for a sparge. Say leave out ~20-25%, or whatever doesn't fit in the kettle during the mash, since the bag of grain takes up volume that's regained once you pull it.
Your ~50/50 mash/sparge volume is not advantageous.

What was your after boil volume on your first batch, or how much went into the fermenter? Maybe you boiled off more and ended up with less than 5 gallons, hence the higher gravity.

For a 5-5.5 gallon batch in your fermenter, you'd need around 7.5-8.5 gallons of water:

1. Grain soaks some of it up, 0.12 gallon per pound of grist
2. You also boil off one gallon per hour, give or take
3. Then there is trub loss at the end of the boil, wort that stay behind in the kettle and doesn't make it into your fermenter

 

[wilserbrewer]

Your first method seemed to work pretty well, I wouldn’t change much unless you want to.

The mash sparge volumes in a recipe are not critical imo, and you can have flexibility to suit you method.

Likely a 90 minute mash is not needed imo, 60 should be plenty unless you have a lousy crush on your grain...

 

[IslandLizard]

unless you have a lousy crush on your grain...

That ^

Finer milled grist speeds up the mash and increases efficiency. 85-90% mash efficiency is very attainable.
For BIAB your grist can be milled quite fine, the mesh bag is the ultimate separator.

 

[RichardM]

I asked for a double crush at the HB store. I thought they did a good job and looked fairly fine, going off some pics I've seen posted here. My thinking on topping up the kettle while the bag was hanging was, why not try to get a little more sugar since it's just hanging there? It made heating to mash temp quicker with less volume. It held temp just fine, but I understand a full volume would probably hold temp better.

BIAB is typically done with full volume, or with some water left behind for a sparge. Say leave out ~20-25%, or whatever doesn't fit in the kettle during the mash, since the bag of grain takes up volume that's regained once you pull it.
Your ~50/50 mash/sparge volume is not advantageous.

What was your after boil volume on your first batch, or how much went into the fermenter? Maybe you boiled off more and ended up with less than 5 gallons, hence the higher gravity.

For a 5-5.5 gallon batch in your fermenter, you'd need around 7.5-8.5 gallons of water:

1. Grain soaks some of it up, 0.12 gallon per pound of grist
2. You also boil off one gallon per hour, give or take
3. Then there is trub loss at the end of the boil, wort that stay behind in the kettle and doesn't make it into your fermenter

I didn't see any reason why I would need to do a 50/50 sparge. I probably was closer to 7 gallons preboil on the 1st one. I left a little behind in the kettle and ended up right at 5 gallons in fermentor. I usually only leave a little beer behind after kegging.