Long story short:
My digital probe thermometer started giving unreliable readings about halfway through my mash, but I didn't realize it until I was sparging. I missed my pre-boil gravity by 11 points and my OG by 10 points.
I am sure it will still be a fine beer, but if I wanted to keep tight to the recipe, what would have been the best course of action, given that I didn't have any DME on hand (a mistake!)?
Should I have boiled it down until I reached the proper OG? If I had done that, how would I have adjusted the hop schedule? Should I have boiled it without hops until I hit the pre-boil gravity, and then followed the hop schedule per the recipe?
As an aside, I have been toying with the idea of getting a refractometer because I hate the process of cooling the wort to get decent readings. This is a situation where, if I wanted to make adjustments, it would have been invaluable. I never would have been able to get an accurate hydrometer reading in time to adjust the boil. Long story long for anyone interested
: The recipe was the Fat Tire AG clone from Norther Brewer. I've been experimenting lately and wanted to try a multi-step infusion (even though I know it's not necessary).
I decided to follow a three-step mash schedule, with the final step to mash out being a decoction. That's both because I was curious to see if the decoction made a difference to the recipe and I had no other way of doing a three-step due to my 5 gallon mash tun. Everything I've read says that the clone is good but not close to the real thing. I thought maybe the optional three-step schedule, with a decoction, might close that gap. After all, Fat Tire has a certain caramel character that decoction could help to bring out.
I was using two thermometers: a digital probe on my HLT (a large canning pot) and an analog dial-on-a-stick in my mash tun (5 gal cooler). Out of necessity, my first mash step was thick (0.8 qt/lb). It was able to hold and support the analog thermometer very easily.
Everything went great and I seemed to be hitting all my temperatures. I hit the first 122 degree step spot-on. For the second step I hit 154 instead of 152. Not perfect but OK. Here is where my temperature readings went a bit off the rails.
When I poured in that second (aiming for 152) infusion I forgot about the thermometer and poured straight over it. I tried to find it with my spoon but had no luck, so I just left it in (I found it by accident just before sparking, which is good because it probably would have messed with my grain bed). So I had to make my digital probe do double duty, moving it between the HLT and mash tun.
While sitting at the 152 step for 60 minutes I got my spare water up to 168 and turned off the heat. But the temp reading kept climbing. 180. 200. The probe was not against the side of the pot. I thought maybe moving it back and forth was causing some sort of lag on the reading. I should have been more skeptical, but instead I turned off the heat and started removing a quart at a time from the HLT and replacing it with cold water to get the temp down.
After adding the decoction, I moved the probe back to the mash tun, and got a reading over 200 degrees! This was while I was trying to bring down the temperature of the HLT. I left the lid off in an effort to get THAT temp down. This is about the point where I began to seriously suspect that my digital thermometer had gone wonky. Luckily, this is also about the moment when I accidentally scooped up the analog one.
Well, the HLT was actually at 100 degrees and the mash tun at 145. I covered the mash tun and put the heat back on the sparge water, which took about 20 minutes to get up to 168. Then I fly sparged as normal and got on with it.
Target pre-boil gravity was 1.045 and measured was 1.034. Target OG was 1.052 and measures was 1.042. BeerSmith tells me my efficiency was ~62%.
This may be a result of my thick initial mash step. After all, I more or less hit the target temperatures for the first two steps, and I *think* I hit the temperature for the mash-out (will never really know). Sure, the mash sat for an extra 20 minutes during mash-out at a low temperature, but that should have no effect, right? One other note: I grind at my LBS and in the past the grind their setup provides has always proven consistent and reliable, so I don't think the crush was an issue.
So two questions for those reading in detail:
- Do you think the efficiency was due to the mash thickness, the temperature issues, or both?
- Given my lack of DME, if I wanted to hit my targets, should I have boiled it down until I hit my pre-boil gravity (making a ~3.5 gallon instead of a 5 gallon batch), or something else?
- Anyone want to buy a 5 gallon MLT? I usually make smaller beers, so to-date this hasn't been a problem, but my next one is a double IPA, and given this experience I think it's time to uprade to a 10 gallon tank! When I bought my gear I didn't know the limits of a 5 gallon cooler in terms of bigger beers. If nothing else, I'll use it as my HLT to hold my sparge temperature and make fly sparging easier.