Hi everyone, relative newbie here. managed to make a speckled hen clone that turned out ok for a first AG brew, and thought I'd attempt a version of Fullers London Porter from Graham Wheelers book. 
what I can't quite work out is that I've inputted the various weights of malts, haven't given it a reference volume to scale it against yet it's decided to scale the malts? is there something I haven't grasped about the the BIABacus?

link to biabacus

thanks in advance

think I've worked it out - it's because I told it I still wanted a OG of 1053. I'll have a play with that, but would still appreciate any advice or opinions. 

I've got a friendly local brewer who gave me some fullers liquid yeast of his own and basically put the whole grain bill into one big sack for me, so adjusting it is probably a bit tricky now.

If I was to brew to a higher OG and then try to dilute down to 1053 in the FV is that likely to work? fiddling around it's going to be  more like 1057.
  

I couldn't work out how to upload the spreadsheet here so i uploaded it to Dropbox and linked to it in the original post

Thanks. I've updated it as you suggested. In some ways I'm not too bothered about not hitting the precise numbers, I just wanted a bit of reassurance that the recipe is likely to give me something that is going to be (potentially) palatable. It is only my 2nd AG brew after all.

I'm still not sure what little tweaks are made to AG recipes to make them work with the BIAB technique, and I'm still not sure which bits of the BIABacus are going to be important to me. At the moment, it's all about making sure I don't overflow the boiler when I put the grain bill in...

thanks. 

sorry for not responding - been away for work all this week. the red warnings say that the mash volume is approaching kettle limits and the vol into full mash is just under the kettle limit - I took this as a warning rather than a "this will not work". Is that right?  

well....it turned out ok I think. it's my 2nd AG so I'm still refining the whole brew day process. I bottled it new years day, and after a couple of weeks it's there or thereabouts. A bit chewy, but I'm hoping it'll mellow a bit in month or two. planning on trying a bottle every week or so until it hits it's stride. A bit fizzy too, but I made a bit of a guess with the sugar for batch priming, going for 80g into about 17L. Bottles are in secondary containment for H&S...

didn't turn out as dark as I was expecting, but it looks and tastes like beer :-)