Did my first robobrew last night. Had a few teething issues, and would be interested in any advice - this was my first 20L AG batch, having only done a couple of 5L BIABs before. In short, the mash temp in the pipe was 4 degrees lower than the set temp despite recirculating, and the sparge stuck (which made recirculating inefficient anyway). I expect the crush or my technique is to blame? Or is the use of rice husk necessary (I didn't use it)?
The recipe was a ESB with 5.5kg grain milled at the LHBS. I've had grain milled there for the 5L BIAB with no problems. In retrospect, the 5.5kg did look like it had a bit too much fine stuff in it. Maybe they didn't check the mill?
The Robobrew manual tells you to fill the malt pipe with grain, then put it into the water. That seemed like a recipe for dough balls to me? So I put the malt pipe in the mash temp water and rained in the grain stirring to avoid dough balls. At 18L of mash water it was very stiff/thick so I added another 2L. The Robobrew manual says 15-20L depending on grain bill, so that should be ok.
The display reported it was holding to 67 degrees well, switching on the 500w heater periodically. But the temp inside the malt pipe was generally 63-64 degrees over the course of the hour's mash. This was despite pouring off 1.5L (which was at 67) and scattering it in the top of the malt pipe every 10m, and sometimes every few minutes as I was trying to get the mash temp up.
I think part of the cause of low mash temp was the pipe wasn't draining well despite my stirring efforts, and the water level inside the pipe was at least a third higher than the water level outside the pipe.
After the mash was complete, and despite my expensive gym membership, it was a heroic effort to lift the waterlogged pipe out of the robobrew with both hands. My long suffering beautiful assistant slide in the stand for me. It dripped slowly, and eventually I had to scrape the bottom of the pipe with a long paddle so it would release the sparge water I was pouring in.
I ended up with a slightly lower OG than expected (but also about 5L less volume than expected). The next morning, there was about a cup of drippings into the bowl from the maltpipe had a gravity of 1.062 which seemed very high to me (ie. lots of sugars left in the grain?).
I realise I'm a newbie with my first big AG batch, and look forward to advice
