Gave the Gruten a run today, just a bog standard ordinary bitter 3.4% used some of the data off the Grainfather write ups, 23 litres fermenter volume, 3.66 kg grain bill, mashed into 20 litres of water, set the efficiency at 70% on Brewers Friend 75 minute mash followed by a 60 minute boil, boil gravity on target, 6 litre sparge.
Target OG 1.035 actual 1.033 this was my fault as I had to much liquor at the start of the boil, fermenter ended up 24 litres.
Efficiency was better than I expected, and could be improved by hitting the pause button a couple of times during the mash and giving the grain a stir, also there was a little silicone grommet which I did not have a clue where it belonged until I started the sparging, it seals around the top of the top perforated plate to stop the liquor running down the sides of the centre tube.
All in all very surprised and happy with the performance for something which is 25% the cost of a BM and half the price of the Grainfather, giving a 70% efficiency rating on the Brewers Friend I thought would be overshooting the mark but turns out it was about right, not bad for a first attempt in uncharted water.