This is how I do BIAB. I wrote it for a friend, but maybe you get some ideas.
I started to brew 3 and a half years ago and I won my first competition this year!
Having said that, please take it with a pinch of salt, I'm still a newbie, I'm sure many things will be wrong.
BTW I take critics and accept advice!
1. MAKING THE RECIPE:
First of all I decide on one style, I read about it, goolge articles, recipes, guides, blogs, forums, etc. and I put together a basic recipe, just with general data: grainbill in %, IBUS, color, OG, hops and yeast to use, water profile... If I have doubts I post in forums asking for directions.
When I'm confident with the recipe, I use https://www.brewersfriend.com/
(you have 5 free slots for recipes, you can reuse them or subscribe) for calculating how much grain I need to achive the desired OG.
When I have the grain I use http://www.biabcalculator.com/
for calculating how much water I need. My kettle is 25L (I make "half batches" = 10L batches) and 35cm in diameter and the boiloff rate is 3.8L/h. If your kettle is bigger, you'll have more evaporation. It depends on the diameter of the pot.
The grain absorption rate that works for me is 0.8L/kg and I usually get 1.5L of turb, maybe less, but I hate to be short so I set the final volume to 12L.
At last I go back to brewersfriend and finish the recipe to the very last detail taking into account the extra 2L of "trub".
For the water minerals and PH I use: http://www.ezwatercalculator.com/
You have to start by getting information about your water supply. Luckily for me I live in the Sydney area. Here water is awesome and the reports are public. Otherwise you can ask in the forum and maybe someone can give you a hint.
But for a beginner, I would just use tap water as is, at least if you live in a place with a very good water supply. If you're making something hoppy, just add 1/2 teaspoon gypsum / 10L to the mash and that's it. Well, unless it is a NEIPA, in that case, same quantity of calcium chloride.
I usually do multi-step mash. That means you start at a temperature and you increase it to the required steps. If you do "traditional homebrewing" with an esky or other container for the mash, you have to add hotter water to increase the temperature. With BIAB it is way easier! You can just do it in the same kettle with the bag and turn on the fire!
In order to not-burn the bag I use bulldog-paperclips on the lip of the kettle to keep it open and "suspended" and a stainless steel steamer-tray/basket upside down on the bottom of the kettle (with a string so I can remove it before the boil).
This is going to be very controversial and there are books dedicated to it, but here are some typical mash steps I use.
WARNING! You have to study which steps to do and at which temperatures for different beers!
Temp: 45 C, Time: 10 min, Beta Glucanase Low: avoid grain gumming up (unmalted grain) / Ferulic rest (increase phenols)
Temp: 55 C, Time: 10 min, Proteinase/Beta Glucanase High: improve head (Warning! thins out body!)
Temp: 62 to 68 C, Time: 60 min, Saccharification/Beta-amylase: extract main fermentable sugars (62=dry, 64=normal-dry, 66=normal-sweet, 68=sweet)
Temp: 72 C, Time: 10 min, Glyco-protein/Alpha-amylase; stabilize head/foam
Temp: 78 C, Time: 10 min, Mash out, improve extraction
Typically you'll do just 2 steps: saccharification and mash out.
During each step I cover the whole kettle with an insulated bag and a blanket. Between steps, while it is raising the temp, I stirr constantly.
I take the bag out of the kettle and turn the gas on so it´s heating up while I do the sparge.
Then I put the bag on another pot with a colander/steamer on top and the sparge water in a third kettle.
I do the sparge with a hose from the third pot to the bag using gravity and pressing the hose to the bag in different spots. Once the 2nd kettle is full, I transfer it to the main kettle and keep sparging.
A simpler way is to just dump the whole bag into a kettle with the sparge water for 20' and then remove the bag and put the sparge-wort back to the main kettle.
The easiest way is to not-sparge at all, just take the bag out and throw the grain away.
Some people sparge with a jug over the bag, the water goes around the bag and you get pretty much nothing.
If you don't do sparge you'll loose efficiency though, but for making 20L that's going to be a "cheap waste".
It's worth saying the grain-to-mash-water ratio is important, so if you don't do sparge, you should keep the "sparge" water out of the mash and add it before the boil. Again... more to read here.
If I need 21L of water in total for my 12L batch (with trub!) I would use around 11-12L for the mash and 9-10L for the sparge, works for me doing BIAB (grains are contained in the bag).
My efficiency % depending on the sparge method:
- No-sparge / jug over the bag = 65%
- Bulk-sparging = 75%
- Hose-sparging = 80%
Most people do 60', but I always boil for 90'.
Always a good healthy rolling boil and the lid off so the DMS can escape.
The longer you boil the more efficiency you'll get because you will evaporate more water and more water washes more sugar (to a point, then you get other things you don't want).
Also it is said you can get some caramelization -> a little bit more color and flavour.
At 60' I usually do the first bittering hops (if the recipe calls for them). I tie a shoestring from one kettle handle to the other one and tie hop-shocks from it. I use cheap thin polyamide shocks, but you can buy brewing specific ones.
At 15' I put my immersion chiller into the kettle in order to sanitize it and 1/2tablet/10L Deltafloc/Whirlfloc if needed.
At 10' I throw in 1/2 teaspoon / 10L of yeast nutrient
To skim or not to skim? I skim. Most people say it's worthless but it prevents boil overs, minimizes trub and some people say it improves clarity and can reduce potential oil/fat that can make your foam disappear quickly.
5. CHILLING AND PITCHING YEAST:
After the boil (and any hopstand if the recipe calls for it) I put the whole kettle inside a big rubber bucket with cold water and a pond pump connected to one of the immersion chiller hoses. I dump the first two buckets of water (I use it for flushing the toilet or washing the bike) and then I put the other hose back to the bucket and add a couple of frozen-esky-blocks. In summer I also put some ice into the water.
When it´s at pithching temp I take out the hop-socks, press them to extract all the juice with my hands very well clean and sanitized, I transfer the wort to the pre-sanitized fermenter, close the lid and agitate it for a couple of minutes (oxygentation). Then I open it again, take the sample for the hydrometer, pitch the yeast and put the airlock on.
If the OG is too high, I add some tap water. I've only done it a couple of times and it went well, no infections. I've read tap water is safer than mineral water, but if you want to be 100% you can always boil the water first...
I have a small bar fridge big enough for my 15L fermenter with the airlock on, a heating pad and an Inkbird controler. I tape the probe of the controler to the side of the fermenter with an insulated pad (neoprene or something similar, a beercoola works well) so it is in contact with the fermenter and isolated from the fridge's atmosphere.
Both the heating pad and the fridge (set to max/coldest) are connected to the controler and the controler is configured with +-1ºC threshold and 3' of compressor delay.
When it has reached the FG (you need a hydrometer for this!) I always bottle.
I reuse glass brown bottles. I rinse them with tap water when I drink them and put them in the dishwasher. Before bottling I rinse them with sanitizer and spray the mouth.
I've done bulk priming a couple of times, but I prefer to prime each bottle. It doesn't take too long for my half batches.
First I calculate the priming sugar https://www.brewersfriend.com/beer-priming-calculator/
for the bottle size, weight it on a drug-dealer-scale from ebay and then I use a modified syringe for repeating the measurement for all bottles. I cut down the tip of the syringe with a cutter so it is like an open cylinder and I adjust the volume with the plunger. Every time I load the syringe I tap it a couple of times and fill it back to the top with a spoon. All my bottles have always been very consistent using this method. I guess if you do more than 10L you'll probably want to do bulk priming (transfer to another container and add all the sugar at once prior to bottling) because priming each bottle is a pain in the ass.
The first time I did it I used a manual capper but the cost of a proper bench capper is negligible, absolutely worth it.
I also label all my bottles. I make the label with paint.net (opensource alternative to photoshop for amateur use), I print them in regular paper at the office (color laser printer), I cut them all stacked and I "glue" them with milk using a finger as brush. Then I press them to the bottle, remove the excess with a rag and that's it. At first they get some wrinkles, but they are gone when it gets dry. The labels stay put and come out very easily afterwards.
If the temperature is not right at my place, I put the bottles in the fermenter fridge. Then standing in the fridge 1 day and boom.
Since I started brewing with brettanomyces ("wild yeast"), other bacterias and funky yeasts I noticed sometimes, some bottles develop a pellicle inside. It's not bad but it doesn't look good. Conditioning with the bottles laid on their side helps. Many belgian breweries do it that way. It's not a must do, but it is a good practice.
I've also reused bottles from funky beers for not funky beers without an issue, the dishwasher kills all.