maevans,

To be honest even though I have a million BIAB's under my belt (literally). I end up either a little high or a little low most of the time. My fellow brewers say that I am a "little off" as well? I try to have the same amount of water each time and I keep the same rolling boil rate. The problem can be the simple as one of those factors being slightly off or low humidity on brew day causing rapid evaporation?

Anyway you look at it, it can be bothersome if your just starting out with BIAB. The way I deal with it is ignore the whole thing. My average pallet won't detect any difference nor will the judge judging my entry. I have added DME in the past. I have also chucked in table sugar or honey. After a while I just decided that I screwed up my "reproduce-ability" more by fiddling with it than if I just spent a little more time at the very onset verifying my starting variables. (water amount, grain absorption, amount squeezed out of mash, ferocity of the boil)?

In short. (too late!) For (me). I just do the best I can and don't fret about missing a number of two. I think that a few degrees off in the mash are more important than a few points in gravity so I really concentrate with mash temps. "Don't worry, relax and have a home brew"! Sorry if I rambled, I do that when I am sober. Luckily that doesn't happen often.

This is a great question maevans and I think Bob has answered it really well.

BobBrews wrote:Anyway you look at it, it can be bothersome if your just starting out with BIAB. The way I deal with it is ignore the whole thing.

If you start with a great recipe, you can actually let it wander quite a way from the intended gravity targets and probably be unable to even taste a difference even if you brewed the beer side by side. So the first thing is not to worry.

My personal preference is to set my numbers up so that it is likely I will have to use some top up water in the fermentor. This is a sensible way to go and it is the way that the BIABacus defaults tend to favour - you should get more beer than expected. However, if I ever was in a situation where I undershot the gravity I wanted, I really wouldn't worry about it and certainly wouldn't do any DME adjustments. Firstly, any single gravity reading you take needs to be at least double-checked. Secondly, DME is not something I really want to be putting anywhere near my all-grain brews.

Dealing with evaporation rates

Evaporation rates will vary a lot. (I'm going to come back to yours though in the next section.) I leave mine on the BIABacus default as this tends to be close to the minimum I will evaporate. So, set your evaporation rate on the low side.

Add your bittering hops at 60 or 75 mins. You should not boil hops for more than 90 mins and there isn't that much difference in utilisation between 60 and 90. So, if you add them at 60, this could allow you to do the following if you could be bothered...

You could, half-way through your 90 min boil (you should be boiling for 90 mins on your all-grain brews) stop, take a volume measurement (which will probably be dodgy as volume measurements on hot or close to boiling liquids are hard to take) and, if there is a big discrepancy going on, you could choose to extend your boil.

It's no point extending your boil after you add flavouring or aroma hops of course.

Personally, even as a beginner, I would not worry about doing the above. Just take your volume and gravity measurements pre and post-boil and if anything is wildy out of whack take a third gravity reading only on well-mixed wort before you make any adjustment decisions.

Where Numbers Help

Numbers help in a lot of ways (see last para above) and are generally much more important when we start out brewing as we haven't developed a feel for things yet. Numbers get us on the right path and tell us when something might be going wrong.

For example, in your post, that 1 L of extra wort on such a small batch size tells me a lot. I'm off for a few days so won't be able to help you with that but there are many reasons why you could have ended up with such a large discrepancy and I suspect that low evaporation probably wasn't the real cause. (Not much point analysing a single brew anyway ).

Where Experience Helps

Experience tells me that I don't need to worry about getting the numbers exact. I need to set them up right but I don't have to worry about the end result being perfect.

Experience helps when you get thrown the odd ball. For example, the other day where massive winds developed just after my boil began. Without experience I would have ended up with an un-boiled beer and been worried about many conflicting factors (low boil vigour but high evaporation rate for example). With experience, I knew that boil vigour is the main need and so floating a large bowl on the wort surface. I extended the boil time to compensate for the time I guessed the beer hadn't been boiling (wasn't keeping too close an eye on it - lol) and knowing that dilution at the end with good water does no harm at all.

Another area where experience helps is to know when you have something seriously going wrong with your ingredients. For example, I recently brewed NRB's All Amarillo Ale, a beer I know well and love, and it had no amarillo character at all. I suspect the hops I was sold were either kept badly or incorrectly labelled. Without experience though, I would have never even noticed a problem, I would have just thought, "What a boring beer."

Where Artistry Helps

Artistry is not my specialty but it helps me in so many ways. For example, when confronted with the above problem, I knew whose posts to read here on this forum and was able to find some solutions to correcting the amarillo problem above. I'm half-way through this process but have already found some amazing solutions.

I also much prefer stealing artistic brewer's recipes. Some brewers have an incredible knack for ingredient combination that seems innate. They can formulate or see a beautiful recipe from a few ingredients but, if you ask them the specifics of the recipe they will often find those questions impossible to answer as they have never had to. To them a pinch of salt is a pinch of salt and a bucket of water is a bucket of water. My thieving from them and asking them lots of questions has taught me heaps.

thughes and BobBrews are very good examples of great brewers who also have the artistic knack. Just today on BIABrewer.info, thughes answered a question I could not have hoped to even consider answering and my initial trials of BobBrews hop vodka with a joshua twist have been totally amazing.

Trialing all this hop vodka and hop tea is making me drink more than usual as well. How good is that?

Sorry for the long post and apologies that I am not going to check over it for grammar and spelling.

Cheers,
PP