So I was thinking about switching from extract with grains brewing to all grain brewing using the BIAB method. I had this idea to use several of the small disposable bags I get for the grains in the extract and grains method instead of a big one for all of the grains. Is there a down side I'm not seeing for this method?
I have been using this method for three years or more, starting off with four bags and then cutting back to three, with between 1.5kg and 2kg per bag. If mixing grain, I split the different varieties equally between the bags. These are what we call laundry bags in Australia (designed to hold delicate items in washing machines).
Initially I used to tie the bags with twine, then moved to zip ties, before eventually sourcing some bags with built in zip closures which are excellent.
Care needs to be taken when adding bags to strike water in order to avoid any dough balls. My method is to add one bag at a time, using a paint stirrer to turn each bag over thoroughly to ensure that all grain comes into contact with the water.
There has been no need for me to reveal my method to fellow AG brewers, and they have given many of my beers the "thumbs up", with none of them querying my procedures. Most of these beers are in the 5%-6% ABV range.
It beats the hell out of lifting one bag, especially when I have nowhere, and I mean nowhere, to install a pulley lifting system. As a matter of fact, I would not be doing BIAB if it were not for the multiple smaller bag method.
In theory this would work.
The only caution would be to make sure your milled grain very well blended to have even portions of each grain in each bag. Since mixing it as a whole as once in the mash would not be an option as easily if it was one a large bag.
Reason for this is to to make sure enzymes from your base malt are everywhere so your mash gets even coverage for conversion.
For example. Say you use 3 bags. 2 have your base malt and the third is filled with specialty grains with no or low diastatic power. The third bags area would result in an unconverted starchy mess.