BIAB 5 gal pot, can you top off?

So my gf surprised me with a kit from the LHBS, but she picked up an all grain one. I've never done all grain; have only done 2 extract batches, both of which I've used a 5 gal pot for then just topped off to get to 5 gals. I only have the one 5 gal pot and a few smaller pots (1-2 gals) that are used for cooking and what not.

I've been reading up on the BIAB method for quite some time & have been wanting to try it so it being all grain isn't the problem, getting 5 gallons out of it is what I'm curious about. If I mash (one pot, no sparge method) about 4-4.5 gals + grains (10.5 lbs) in the one 5 gal pot I have, could I then top off to 5 gals in my fermenter with bottled water? Will this ruin my efficiency?

Another alternative that I'm hoping to avoid is to just split the kit into two 2.5 gal batches, but I'd like to avoid doing twice the work if at all possible. Doing it this way I would try and knock out both 2.5 gal batches in the same day and combine them in the same fermenter. Any flaws in this plan if it comes down to splitting the batch?

Like I said, I have no experience with all grain so any suggestions on how to get the most out of this kit without upgrading my equipment would be great.

You might not get the efficiency that you could by doing a concentrated mash and then topping off but you certainly can make quality beer that way. I would expect you to have trouble getting 4-4.5 gallons plus grains in the 5 gallon pot. You might get 4 but I usually shoot for a little less than that because the grains do take up some room and...if you have too much liquid in when you start the boil it will spill over. Guaranteed. Watch it really close as it comes near the boil.

I might suggest that you start with about 3 gallons of water and put the grains into that much. Have another pot (smaller is OK) of water heated to near the mash temp (usually between 152 and 156F) so you can add more if you still have room in the pot after adding the grains. When you pull the bag of grains out, let them drain for a few seconds and then slip a bowl (I use plastic and I have a colander inside to hold the bag of grains suspended above the bottom of the bowl) under it so you can set it down. Let it drain into the bowl and then use a pot lid to hold the bag of grains in place as you drain the wort into the boil pot. Repeat as necessary, using the pot lid to squeeze out every bit of liquid you can.

You can also use a second pot to collect more wort that you can get by adding water to the bag of grains, stirring it in, and then return to the drain and squeeze routine. This will give you a little better efficiency an you can boil this wort in that separate pot, chill it, and add it to the fermenter.

Hmm good to know. Topping off once the grains are in sounds like a good way to go for starters. I have some fermcaps so hopefully I can fill the pot almost to the brim & still not make a mess.

Would letting the grains sit in the smaller pot with ~152 degree water until its time to chill and mix in the fermenter help my efficiency any? Beersmith has it calculated out at 6.4% abv (can't remember og off the top of my head) with some added grains I have laying around. Hopefully this can help offset any poor efficiency. I'd be happy with something around 5%

Acyr90 said:

Hmm good to know. Topping off once the grains are in sounds like a good way to go for starters. I have some fermcaps so hopefully I can fill the pot almost to the brim & still not make a mess.

Would letting the grains sit in the smaller pot with ~152 degree water until its time to chill and mix in the fermenter help my efficiency any? Beersmith has it calculated out at 6.4% abv (can't remember og off the top of my head) with some added grains I have laying around. Hopefully this can help offset any poor efficiency. I'd be happy with something around 5%

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You can try leaving the grains in the smaller pot at mash temp for a while but eventually you need to bring that wort to a boil to kill off the bacteria that are likely in the grain. Then you have to chill it again. If you don't boil it you can expect a lactobacillus infection in your fermenter within 2 or 3 days.

Ahh that makes sense. I might suck it up and just make two separate batches and combine them to get the most efficiency possible. Anything wrong with having 2.5 gals sit in a fermenter while I brew up the other half? I'm estimating it being in there for 3 or 4 hours before being able to pitch the yeast.

Acyr90 said:

Ahh that makes sense. I might suck it up and just make two separate batches and combine them to get the most efficiency possible. Anything wrong with having 2.5 gals sit in a fermenter while I brew up the other half? I'm estimating it being in there for 3 or 4 hours before being able to pitch the yeast.

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Nothing wrong at all with topping a fermenter...you can also go as far as adding additional wort the folloeing day IME...some refer to this as a Texas tow step...the wort is brewed in two stesp and added to the fermenter as it is available...within a day I would imagine.

I might do that. Another question, will my efficiency be a lot lower if I try and use all the grains in less than the appropriate amount of water? Less water for the sugars to absorb into, under-utilizing the grains, etc. My OG is sky high when I have starting size set to 4.5 gals, close to 9% abv. assuming 70% efficiency. I'd be happy with 55-65% for this batch, is that reasonable when using such a small amount of water for the mash? (~4 gals, topped off to 4.5 for the boil, topped off to 5 once in the fermenter.)

I did a BIAB 5 gal batch with a 5 gal pot. I maxed out the pot and then while my bag was draining over the pot I poured hot water through it and filled the pot back up for the boil. My efficiency was low around 60% but other than that was fine.
When I do a 3.5 gal batch in the same pot I have been getting 75% efficiency. So it does make a difference.

Hmm that doesn't sound all too bad, I'll run Beersmith at 60% and see if the numbers still look reasonable.