a few starter BIAB questions

I live in an apartment, and just did my first partial mash recipe, some wheat and two row for a hoppy wheat recipe I made up. It got me interested in doing some more all grain brewing, but obviously I'm probably limited to smaller batches.

So I have a few questions...

#1: I have a 5 gallon stock pot. What is the largest all grain BIAB volume I could reasonably expect to create? Would 3 gallons (to then ferment in a 5 gal better bottle) be unreasonable?

#2 how do you, mid mash, figure your efficiency? I know there's an iodine test that can tell you if conversion has happened, does it also tell you enough to know to what extent it could happen?

#3 if you were to reccomend an easy AG recipe for a newbie (done 3 extract brews thus far, want to get a small taste of the other side), what would it ve? BCS is in my Xmas list, and that'll be a great resource to see the difference between AG and extract, as well as just reminding me of all the different types of beer that can be brewed

Thanks for your help. This site as a whole has been extremely helpful and positive... Hope someday I'm knowledgeable enough to contribute back into it

Re: #1, I just (mostly) finished a batch of a PM Bock with my 5 gal pot. I started my boil with about 4.1 gallons in it. This was completely terrifying, but largely thanks to the fact that my stove is nearing its limits boiling that much wort, there weren't any boil-overs.

Based on this, I think I could probably pull off a 3-3.5 gallon full boil batch in my kettle.

Re: #2, I don't think there is any way to do this. The iodine test just tells you whether there are unconverted starches still in solution (I think). It doesn't actually measure the amount of starch, or the amount that's still stuck inside the grains.

Why do you want to do this? I'm not sure I see a reason not to just wait until the end of the mash to check the gravity. You still have time to add extract or reduce the size of the batch to make up for unexpectedly low extraction.

Can't help on #3 as I've not done AG at all.

You could do a Maxi BIAB, which if understand it correctly, is BIAB in a smaller vessle with sparging and dilution. Google "Maxi BIAB guide" and you'll find more information.

#1 boil volume is typically limited by how much heat your burner can produce. My max is 3.5 gallons. Gravity can actually go down if you have too much grain because sugars get tied up in the grain. For no sparge any more than 1.75 lbs / gallon will reduce the initial gravity. For 1 sparge it is 2lbs/gallon and for 2 sparges it is 2.25lb/gallon. (Blog post with details later this month)

#2 the iodine test checks conversion efficiency. A 60 minute mash at 151 or higher, or a 90 minute mash for lower temperatures will almost always result in near 100% conversion. Most people don't check this. Lautering efficiency is the main driver of brewhouse effiency and is determined by how you sparge.

#3 any recipe without oats or wheat will be easy. What type of beer do you like?

I would think 3 gal with a sparge would be doable in a 5 gal pot. I have a 6 gal pot and never come close to the top. 3 gal or so water into the pot and mash. then the remaining water I do a dunk sparge and pour that water into the boil pot then start the boil.

I just mash for 90 minutes. It gives me time to do other things around the house.

For an easy recipe do a SMaSH. Single Malt and Single Hop. My most recent one was 6lb of Marris Otter and .5 oz of willamette at 60 min 10 min 5 min and 1 min. This was a 3 gal recipe. It turned out great.