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Hi all

With me planning my 1st BIAG at the weekend I'd better try and get things planned out before hand so......
With my 15ltr stockpot I plan on using 2kg of grain so how much space should I allow for displacement in the pot? I don't want to be topping up once I've got the mash on so what starting volume of water should I aim for that would then fill my pot once I've added my grain? Would 12ltrs be enough or could I get away with 13 and not risk overflowing the pot?

Cheers Tom

[Admin Note: I have moved this to the Mini-BIAB forum Tom as you will get more specific advice there. Good luck on your first brew. Nuff.]

Ralph's the expert on Mini and Maxi-BIAB's so he will set you straight.

All I can say is that you should allow more space rather than too little. You don't want to lift your bag up and have it spill all over your stove!

Ralph has lots of crafty ways of increasing how much wort you can "score" when not doing a standard (full-volume) BIAB. These all involve topping up but not during the mash.

I have never done a Mini or Maxi-BIAB but am constantly impressed at the yields. Make sure you read Ralph's guides that are stickied in this forum a few times. Any good guide I have read takes a while to read and absorb. I usually start doing this about 5 minutes before I need the knowledge .

Will look forward to reading how it all goes Tom.
PP

I've found this, http://www.rackers.org/calcs.shtml "can I mash it" near the bottom of the page. I don't know how accurate it is but it's supposed to take into account absorption too

Cheers Tom

You can also use The Calculator to determine what the "approximate mash volume" is going to be. Cell B21 will tell you the total volume occupied by your mash (water + grain). I've found that it is quite accurate. If the "approximate mash volume" is larger than the volume of your kettle, just omit adding the additional water (i.e. if mash volume is 17L, I'd omit ~3L of water if using your 15L kettle).

But to answer your question directly, by looking at cell B21 in The Calculator, it looks like the "grain volume factor" is 0.66 L/kg. So for every kg of grain, your mash volume will increase by 0.66 L. In your case, 2 kg will add 1.32 L to your mash volume.

Thanks for that BrickBrewHaus. It's just confirmed the figure from the one I found. It came out at 13.84ltrs so as near as makes no difference it's the same
Happy days, one less thing to worry about

Cheers Tom

Its always nice to have two different sources give the same result

Going back to that brew that you did, filtering the wort through some voile. You said to clean it out 4 times to get it all through. To give me an idea, how many kg of grain did you mash that time?

Cheers Tom

I mashed ~3.1 kg of grain in that beer. Recipe here.

So I might get away with 3 filter cleans if I'm only using 2kg of grain? Whatever makes my process that little bit easier is good Can't wait to get cracking

Cheers Tom

I guess the amount of hot and cold break is somewhat dependent on the amount of grain used, but the trub that you'll be filtering is also contains hops (if you don't use a hop sock). So yes, you might have slightly less trub in your kettle.

I can't remember where I've posted this, but somewhere I mention (and I've seen PP's post) that this method is a giant pain in the ass. The reason I tried this in the first place was to eliminate the whirlpool rest and siphoning step in an effort to save time(i.e. make the brew day shorter and easier). I easily spent just as much time using this "filtering" method. Trust me, once you get just a little bit of trub in your filter, the flow of wort through it REALLY slows down, and gets to the point where it doesn't flow at all. At that point you have to clean it out, I also made sure it was thoroughly sanitized, and start the process over, and repeat 4 times. I'm not saying not to try it, I'm saying that if you're looking to make your brew day easier, this may not be the way to go. But give it a shot once, I did, and figure out for yourself if you like it.

I was hoping to cover the top of my fermenter with the voile which should give me a greater surface area to work with. I'm sure it's not that simple though. My prime concern is reducing the ammount of hot break I allow into the fermenter. I'm not really that bothered how I do it

Cheers Tom

Yeah, as long as you make sure your material is secure and doesn't fall inside (I assume you're using a wide mouth fermenter like a bucket), that should work fine. You might find out its more trouble than its worth, but you'll never know unless you try. Good luck.

Yep, it's quite wide. I've yet to get my bungee strap to secure it around the top of my stockpot though. It would be just my luck if the whole lot fell into the fermenter

Cheers Tom