First BIAB - I screwed almost everything up and was 20 gravity points out

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May 27, 2009
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I've done a few partial mash kits that have turned out OK but today I did my first BIAB with a DIPA kit that included 7kg of grain. The recipe called for 17L strike water and 17L sparge water. I had to use about 30L of strike water as there were lumps due to how thick the mash was.

I thought I added too much water as I forgot to account for the loss due to hop debris in the boil kettle so I didn't sparge. The grain bag was fixed to the bucket insert so I didn't remove it to squeeze as it's not my equipment and didn't want to break anything.

I had to add a about 5L of water to make 23L fermenter volume like the kit says but instead of having an OG of 1.071 like the recipe says, it was only 1.050 so I had to add 1KG of dextrose just to meet target gravity. That's about 20 gravity point out...

There is also a massive amount of hop debris from the 150g whirlpool addition. About the bottom 40% of the fermenter is hop debris even after using Irish moss in the boil and letting it settle and discarding about 3L from the bottom of the boil kettle.

It's in the fermenter now with yeast pitched sitting in the fridge. Should I just throw it out and start again to free up space in the fridge? I only have room for 1 fermenter in the fridge and it's summer time now.
I wouldn't throw it out. If your expectation is to get drunk quickly you will be somewhat disappointed but a 1.050 beer is pretty drinkable. Let it have 4 days in the fridge, then take it out to finish fermenting. The fermentation should have slowed down enough by then that you won't be creating off flavors. Then make a new batch.

A recipe is only a record of what someone else has done, not necessarily a guideline for what you should do. The person who wrote it used a conventional mash tun most likely instead of BIAB so the numbers are off.

For your new batch, you know to use more water at the start. If you have a way to mill the grains finer that will help with the mash efficiency but if not, mash longer. Nothing in brewing says you have to mash for 60 minutes exactly. Your grain crush may dictate a 90 minute mash or if really fine, maybe only a 30 minute mash. A sparge step will improve your brewhouse efficiency as you will be rinsing more sugars from the grains. Expect a 5 to 10% bump in efficiency from that. Squeezing speeds up the draining of the bag of grains but if you can just hang the bag and let it drip out you will get nearly the same amount of liquid out. If you can't hang the bag (fastened to an insert), just set it over another pot or a bucket to collect the extra liquid. This will work for a sparge step if you only are able to pour water over the bag of grains. This will eliminate having to add water which simply dilutes your wort.

Leaving the hop debris seems like a good idea but that often is mostly wort so dump it all into the fermenter and let the ferment complete. Being careful you can leave the hops in the fermenter while still collecting more beer. Those 3 liters you threw out because of the hop debris was pure waste and probably contained 2 1/2 liters of wort.
Thanks, that was very helpful! I'm wondering what will happen with the 1KG of dextrose I added. I know that will thin it significantly as that's a big gravity increase with just dextrose. Maybe I should double my dry hop amount to try and somewhat hide all that dextrose.

Or should I buy some DME and stir that into the fermenter to boost gravity to 1.080+ to cover up some of that dextrose?
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