First BIAB... with a few questions.

[Redpappy]

i just finished my first BIAB 1 gal. Since this is my first, and I’m still in the learning curve I do expect hick ups. But have to admit, it was fun. I do understand some of my numbers will be off,brewing on a electric stove, I used Brewers Friend receipe tool, as a guest. So now I will go into the stats:
Strike temp was 156 mash temp came in at 152. I placed my kettle in the oven ( pre heated to 170) after 60 min, mash temp was 149.
Total water amount was roughly 2.6 gal,pre boil was at 2.5 gal
Grain bill came in at 1.75 lbs

According to Brewers Friend, 60% efficiency boil gravity 1015 OG 1039 FG 1011
“. “ 80% efficiency boil gravity 1020 OG 1052 FG 1014


My boil gravity was 1020 my OG 1034

After I topped off my fermenter to the 1 gal mark, I finished emoting the kettle in a measuring cup and measured what I had left. I ended up with 5 cups of extra wort. So I know my calculation for boil off was off, and my estimate for trud was off a tad bit as well.

Questions, 1. Would 5 cups extra water cause the low OG?
2. I did a 60 min boil, would a 90 min boil been good to do if I had noticed earlier that I was not on target?
3.Once I got my boil gravity, I started to change the efficiency till it reached my boil gravity, is that the best way to figure out your efficiency?

 

[chickypad]

In your case yes, the 5 cups matters. You targeted 1 gal and finished with 1.31 gal or 30% over. 1.034 of 1.3 gals would translate to about 1.044 at 1 gal.
You could have boiled off longer if you knew ahead of time you were over volume, but you should do your hop additions at the proper time to keep the recipe the same.
Probably the easiest way to figure your efficiency since you already have the recipe in Brewer's friend is to change the batch size to 1.31 gal then adjust the efficiency to match your actual measured final OG.

 

[wilserbrewer]

Small batches are tricky in that boil off can be a very large percentage of total wort.

While you can sharpen your pencil and try and perfect your calculations, I believe it is just as important to measure volumes along the way and make adjustments accordingly.

If over volume you can boil longer, you can add the early or first bitter hops then extend the boil, but time the late hops with the end of boil. Boiling the bitter hops longer doesn’t matter much imo.

If short on volume preboil, you can sparge a bit more wort through the bag.

An easy way is to mark your brew spoon with pre and post boil volumes to gauge where you are.

This can make it very simple...mash in short on volume then do a small sparge to pre boil volume, then monitor volume during the boil to post boil volume...all done without a calculator or measuring any water, very simple.

 

[HogFan07]

I did my first official BIAB this weekend and had similar issues with my set up. OG came in at 1.042 I was aiming for 1.05 and had a decent amount left in the pot.

Afterward (while it was on ice) it dawned on my that had I reduced it the OG should have gone up. Overall pretty happy with the results and learned that I’d keep it on the boil while the sample cools I can continue to boil if needed and save myself.

 

[HogFan07]

If I added sugar to the fermentor would that increase the OG? Or would it be FG? Or would it be a waste of time?

Probably just gonna roll with the punches but that if it were a possible fix it would be nice to know if I ever needed it.

 

[Redpappy]

https://www.beercraftr.com/correct-original-gravity/
I have read where other people have use DME to correct a low OG. My last 2 1 gal batches that I have done came out better, well at least better on the numbers. Light DME seems to be the all go to for small goof ups.

 

[AHagne]

I have brewed about 10 batches in a BIAB system. After not keeping accurate notes of every batch i got varying results. I also changed systems which resulted in a trial-and-error phase which was not that succesfull. The brewspoon tip given earlier is great, but if you are ‘hooked’ and will be brewing a lot i would recommend buying Beersmith. After i did this i have spot on OG, water levels etc etc. They have a 21 day free trial if you feel like testing it.

 

[RM-MN]

If I added sugar to the fermentor would that increase the OG? Or would it be FG? Or would it be a waste of time?

Probably just gonna roll with the punches but that if it were a possible fix it would be nice to know if I ever needed it.

Any batch where you add a fermentable to the wort it will increase the OG. Depending on the fermentable it can increase, decrease, or leave the same FG. Sugar is likely to decrease the FG. Some malt extract will have unfermentable sugars and can increase the FG.