When is it ok?

So I brewed yesterday and was rushing towards the end. I brew 2.5G batches and my batch came up short on water. Ever since I started doing a full BIAB method with just a mashout and no sparging (which has actually increased my effeciency), I've been coming up short on water at the end. Not sure why Beersmith 2 keeps telling me low numbers on my volumes. I always keep ending up short even though I set the mash profile to BIAB. I also have my equipment profile set up properly too....but all that is beside the point.

The question is, at the end I was over my measured OG a bit, because I came up a touch short on water. Ended up at about 2.1 or 2.2 gallons and an OG of 1.054....estimated was 1.052. If I had topped up I woulda hit my marks perfectly. I was in a rush though and chose to leave it be. I was wondering if it would be ok to siphon in some more (boiled, cooled) water during fermentation or after fermentation to set it straight or if it's not ok to do that and I should just leave it be.

Thanks in advance.

YOu might be having more losses due to grain absorption/hops loss.

I wouldn't worry about a 54 vs 52. You will be in range for your style which is what is important.

You can add or not add. The numbers are such that it probably won't make much of a difference either way.

Thanks for the response.

I think I'd like to add just to get the 2-3extra beers in there since I brew small batches.

I had to adjust my grain absorption a bit in BeerSmith2. It can depend on your area (dry or not) as well as your normal crush. Check where your numbers get off (After mash in, after Boil, etc) and adjust what you need to for your situation. The default numbers are close, but need to be adjusted for your particular area/equipment/situation/etc. It's under tools->Advanced. I don't remember the default, but currently have BISB Grain Absorp to 0.5000 and Grain Absorption to .9600. I think it was the BIAB setting that made the difference, but don't remember off the top of my head.

You also might be boiling off lee water than expected.

Short answer, try starting with a little more in your pre-boil volume.