Large scale cold brewing - Mesh bag technique - What size mesh is best? I'm looking to upscale our production of cold brew to batches with a 1000L yield, using a ratio of 1:12.5 to make a ready-to-drink coffee for bottling. Currently we run batches of ~40L through a large stainless 40-micron mesh conical filter with good results, however this won't scale so easily as the mesh is really expensive. I'm thinking that making large batches by steeping coffee in big mesh tea bags will be the easiest upgrade. I'm also assuming that a secondary filtration will be necessary, but that's a separate question.

What sort of mesh sizes and materials are best for balancing yield with how fine the filtration is? 
Thanks!
I have had bags made up in China. 30cm x 30cm 100 micron is best for stepping. Put 5kgs of coffee in each bag and filter it a second time straight out of the tap.

Ohhhh and never squeeze the bags.