Gravity Is Incredibly Low - Salvageable?

[Alex Kirk]

First time doing an all-grain brew with my new mash tun (one of the 10 gallon Gatorade coolers with a spigot/filter installed at the bottom). I'm doing a Gose, with 3.5 lbs each of wheat and pilsner, with a target OG of 1.035.

After getting my 2.5 gallons of mash water up to ~160, I put it into the container, dumped the grains on top of it, and let it sit for 60 minutes. Took 5 gallons of sparge water to ~145 (the recommended mash temp for the recipe, figuring that the grains and the tun were already hot), let them sit for 15 minutes on the grains, and collected everything in a 6.5 gallon fermenter bucket I had sanitized for the purpose.

I think I made a pair of mistakes, since my gravity read out at 1.014:

* I probably should have had considerably hotter sparge water
* My efficiency numbers must have been off; I was targeting ~5.7 gallons of pre-boil volume, and I cut off my mash tun after coming back in the room and seeing that I had ~6.5 gallons of wort.

After dumping some of it to get it to even fit in my boil kettle, and getting to a brief rolling boil (all that's necessary for the recipe), I've got ~5-5.5 gallons of super low-gravity wort.

Is it even possible to make a sufficiently high-gravity follow-on wort to bring what I just made back up to my target of 1.035? If so, can anyone help with the calculations for how much grain and water I should use to do so, or point me at a calculator that would help?

 

[kh54s10]

Added 160 degree water then dumped the grains on top. Did you stir?
What was the temperature of the mash?
Sparge water temperature is not critical.
You couldn't fit 6.5 gallons in your pot? I need 7 gallons preboil..
Brief rolling boil? What was your hop schedule?
Check out the Brewer's Friend recipe calculator.

Get a bigger pot for one thing.

Crush, how was the wheat crushed? It is a smaller and harder grain so getting a good crush is either by milling twice or tightening the mill.

 

[Matthew Nelson]

The problem is in using a spigot filter and not a false bottom. The fluid dynamics of that setup does not allow even flow of sparge water across the entire grain bed. I bet if you tasted the grist in direct line with the spigot and then tasted the grist along the sides the latter will taste very sweet compared to the former. I had a similar problem. I was able to compensate by increasing my water to grist to 2.5 to 3 quarts per pound and keeping the mash pretty sloppy during the sparge. Until you get a false bottom expect a much lower efficiency.

As for recovering the gravity still trapped in the grist you can stir up the grain bed and treat it like a batch sparge. If you want to combine it with your first draw expect to have a really long boil to get rid of the gallons of extra water. Probably better to make up for the lost gravity with DME or DME plus sugar.

 

[doug293cz]

Can you give us more details on exactly how you sparged? It's not at all clear from your post. What you wrote could be interpreted as a no sparge process, which will have lower efficiency than a sparged process.

However, whatever your sparge process was, it's not enough to account for your low pre-boil SG. I estimate that your conversion efficiency (what percentage of the available starch that you converted to sugar in the mash) was 43% or lower. This is really terrible, as conversion efficiencies should be at least 90%, and can easily be better than 95% for a good crush and mash.

What did your crush look like? Did it look like there were a lot of intact kernels? Did you measure the temp of the mash after you had stirred in the grain? This is the most important temp in your process. Have you checked the calibration on your thermometer? If it reads high, you could be mashing at a lower temp than you thought.

145°F is a pretty low mash temp, and gelatinization (the first step in the conversion process) will be significantly slower at that temp (if you even reached that temp) than at warmer temps. Poor crush in combination with low temps might be the biggest detractor to your conversion efficiency.

Brew on

 

[Alex Kirk]

Looks like there are a lot of little details that I got wrong here.

* I did not stir after putting the grains in for the mash. Combine this with the geometry of the tun as pointed out above, and I probably got a very uneven mash (and may have missed lots of the sugar that was converted in the process).
* I didn't check temperature of the actual grain bed, either - I just relied on the calculations from the Brew365 mash calculator. I actually had a second batch of grain with the same wheat/pils ratio, just 9 pounds of it (that I'd had milled and didn't use for 2 weeks, and thus is oxidized enough I don't want to go to a finished beer with it), and this morning I heated 2.3 gallons of mash water to 160, poured in the grains, stirred...and read 140 on my thermometer. I brought two separate .25 gallon batches of water up to boiling and put them in, and am still reading 140 on the temp. I think this particular thermometer reads a bit low, so I'll be eager to see the OG straight out of the mash in ~20 minutes.
* My sparge process was literally just dumping 5 gallons of heated water on the grain bed and letting it sit for 15 minutes. Again, no stirring at all, so it wouldn't surprise me if I had a bunch of sugars on the bottom of the tun that didn't make it out the spigot.

FWIW the crush seemed pretty solid on both batches - the nice thing about being in Atlanta is that I have several quality LHBS options.

I'll post details on this second round of wort once I have them. Hopefully I can get a lot closer this time, so that I can do a proper follow-on batch with fresh grain.

 

[kevin58]

You also want to pre-heat your cooler mash tun. A lot of heat from your strike water will be absorbed by the cooler.

 

[balrog]

Definitely stir, not just dump in grains. Stir again prior to first drain -- and do a drain before dumping in sparge water. If nothing else, you'll see how much sparge water you need after collecting first runnings.

By dumping in water on top of mash without doing first runnings, you're diluting entire volume, then draining 6.5 gal means all the sugar is in that volume, then you say you dumped some to fit in kettle which means you dumped sugars. I think you definitely need to get a handle on the volumes & as mentioned above the crush. But stir that stuff up. Couple times. Check that thermometer too. It should have moved off 140 after adding a couple quarts of boiling water.

 

[kh54s10]

Your crushed grains are fine, if they are not just sitting in an open container for about a month, maybe more.

Here is a video on doing a Batch sparge all grain:

You can skip the mash out step it is unnecessary.

 

[Alex Kirk]

Measured this morning's mash runnings, and they came out at a 1.060, with about 1.5 gallons on ~2.75 gallons of water put into the system. I had to leave for an early lunch meeting immediately after draining the mash water, so the tun sat for another 3 hours before I got back to it. Added 3 gallons of water brought to 175, stirred it up like crazy, let it sit for ~20 minutes, and got ~2.6 gallons out that measures at ~1.012.

Meanwhile, I've been a bit concerned about my hydrometer - it was bubbling when I put it into my wort yesterday, I had knocked it and the cylinder it was in over accidentally since my last brew - so I took a reading on a Belgian Tripel I've had going in the basement for the last 8 days. It measured at 1.000, which is absurdly low for something that started life at 1.090 (and that tastes like a Chimay - WLP500 for the win!). From there I put in tap water, which came out literally off my scale, close to 0.980, which seems to confirm that the hydrometer is busted. Funny thing, if you take the 0.020 difference in where the hydrometer is reading vs where you'd expect water to be, and add it to my 1.014 OG from yesterday, and it comes out to basically spot on to my original target gravity of 1.035.

I think at this point I'm going to pick myself up a second hydrometer and see how yesterday's batch (which has been airlocked away in a fermenter in the basement) reads, and hopefully just pick up where I left off if it really is measuring equipment failure.

Thanks to all for the responses, this forum has been an excellent community full of helpful folks.

 

[Alex Kirk]

Got my new hydrometer, and suddenly my wort from yesterday read at 1.030 - pulling just from the top without any stirring, which I suspect is actually a bit low given sugars settling at the bottom of the bucket after sitting for over a day. Today's mash read at a 1.086 after stirring, and the sparge was a 1.036, again after stirring (those two I don't plan to actually use, so it was easy to use an unsanitized tupperware to stir them up and pull enough out to pour into the cylinder for hydrometer measurement). I'm going to go ahead and put yeast on yesterday's wort and call the whole thing a learning process.

 

[RM-MN]

I have a theory about hydrometers. I think that when you only have one they get lonesome and depressed so badly that they commit suicide. If you buy two, they have companionship and never commit suicide. At least when I bought two after breaking one, that has worked out and I have one to use if the other should happen to break.

 

[balrog]

I have 3. The original standard old kid on the block, and two expanded range--one for OG one for FG--as the new kids.

I keep waiting to see how they fare on the playground together, whether they'll always gang up 2 on 1 or something. But since I usually only use orig & OG, or orig & FG, they've never shown signs of this.

I'm keeping a close eye on them tho.

 

[balrog]

And I think all 3 of them are scared of that refractometer kid.