Hey there! I've been brewing for years now and finally made the leap into getting a Grainfather, thinking it'd get me more reproducible and consistent results. My first two batches through (roughly 5%, 23L batches of pale ales) were resounding successes. I didn't have any issue with the equipment, hit my OG within a point, and finished up precisely where I wanted to. However, I also make a lot of low-gravity beers (bitters, berliners) and, because I both wanted to keep those and try smaller 10L batches, I bought the smaller 'micro pipework' (Micro Pipework) and every batch I've made with this has come in drastically under-gravity. Made a 23L berliner with a 3.2kg grain bill which came in at 1.028 instead of 1.037 and just mashed and sparged a 10L batch of a ~6% robust porter that I expected a post-mash gravity of 1.045 but, according to my (sometimes incorrect but never THIS far off) refractometer is showing around 1.020. Again, I haven't had this issue with larger batches, so I'm suspicious it has something to do with the smaller overflow pipe and/or just smaller batch and an improper amount of water somehow.
So all that said, does anyone have any experience with smaller grain bills in the Grainfather and have an idea as to what might be happening here? I think I'm following all the instructions properly and both BeerSmith and Grainfather's recipe calculators are roughly coming up the same. For the 6%, roughly 11L porter I just mashed/sparged it called for 10.8L of water for the mash and another 6.8 for the sparge to get me to 15.3 for the boil. I ended up about 500ml short so added that to the end of the sparge, but, sitting right at about 15.5L, I'm WAY under-gravity. I know the Grainfather has/needs about 3.5L of dead space beneath the mash tun, but is there a chance I need to be adjusting something differently to support these low-gravity/small-batch beers? I'm really getting tired of REALLY small beers or dumping
So all that said, does anyone have any experience with smaller grain bills in the Grainfather and have an idea as to what might be happening here? I think I'm following all the instructions properly and both BeerSmith and Grainfather's recipe calculators are roughly coming up the same. For the 6%, roughly 11L porter I just mashed/sparged it called for 10.8L of water for the mash and another 6.8 for the sparge to get me to 15.3 for the boil. I ended up about 500ml short so added that to the end of the sparge, but, sitting right at about 15.5L, I'm WAY under-gravity. I know the Grainfather has/needs about 3.5L of dead space beneath the mash tun, but is there a chance I need to be adjusting something differently to support these low-gravity/small-batch beers? I'm really getting tired of REALLY small beers or dumping