4 stalks of rhubarb is what I used for 5 gallons, and came out nice and tart, but not overly so. I fermented in 2 5gallon fermenters, the wlp001 came out great, but I fermented the other with wlp051. I always make 10 gallons, and split it into 5 gallons, so I can use 2 different kinds of...