Lower than expected OG and other issues

[BurningMountainBrewer]

Hello everyone. I'm new to the HomebrewTalk community but have come to the forums looking for specific information from time to time.

I've been extract brewing for several years and made the switch to AG recently. Yesterday was my 3rd attempt and there were several issues that I'd appreciate your feedback on.

Things did not go smoothly from the start, as I did not check to make sure I had enough propane for the entire process. I was able to heat my strike water up to 180 degrees (4 gallons for 12 lbs of grain) before I ran out. I'm using the cooler mash tun and after adding the grain to the water in the cooler, the temp was 154 degrees. So all good there.

I had to run to the store to refill the propane tanks during mash. By the time I got back and was able to heat the 4 gallons of sparge water, 90 minutes had passed. So the mash sat for at least 90 minutes. While I don't think that, in and of itself, was a problem, the temperature of the mash dropped to 145 degrees.

I did not have water heated to mash out. I tried heating up a quick tea kettle (I know, what??) to boiling to raise the temperature up but of course the volume of boiling water I added to the mash was way too low to make an impact.

When I finally got my sparge water up to 180 degrees and added it to the mash, the highest temperature I measured was 168 degrees. I'm not confident that this was a true reading and I think it was more along the lines of 165-166 degrees.

I collected 6 gallons of wort. Though I could have collected more, I stopped at 6 gallons. The rest of the process went smoothly and I ended up with 5 gallons of brew to ferment. When I tested the gravity, it was 1.050. The target was 1.065.

So, there were several issues with this brew and I'm wondering which (if any) may have caused the lower than expected gravity reading. Thanks for your patience with this long post!

 

[enganeer]

Newbie to grain brewing also.

Hard to say when the temp drop in the mash below 148°, if after 60 min then your probably good, if it dropped faster than that, you might have lost some of potential sugar conversion in the mash.

Was 6 gallons of pre-boil the target or could you have sparged some more water to extract some more sugar and then boiled it down more to 5 gallons?

Also what was wort temp did you take the measurement at? There is an offset from the calibrated temp of the hydrometers.

 

[kh54s10]

Several things to note.

Is your grain very cold when adding to the mash? I only need the strike water to be about 168 - 170 degrees to get a mash at 154. Try pre heating your mash tun.

The extra time for the mash should not be much of a concern.

Nor would be the drop in temperature.

Are you fly sparging or batch sparging? If batch sparging you can skip the mash out. You go from mash to boil quickly enough there is no need to stop the action with a mashout. In the short time there will not be much difference as there would be with an hour long fly sparge.

Add the sparge water, then stir very thoroughly to get as much residual sugar into solution as possible. The vorlauf and drain.

It has also been shown that sparge water temperature is not critical. I have done a few where I just sparged with the heat remaining in the HLT water.

Low OG is most often traced back to a poor crush. Were the grains milled well, that all the grains were cracked open?

 

[bucketnative]

The most common reason for poor mash efficiency is the grain crush. Too coarse, and you end up with a low OG. I had this problem quite a bit with my LHBS mill. I got myself a corona mill, and my efficiency went way up. (Note, the corona mill also made brew day a bit more tedious, as you get quite a work out milling 12 lbs of grain!).

The 90-minute mash and temperature drop did not cause the low OG. Nor did the mashout problem.

I suggest you read Denny Conn's method for batch sparging: www.dennybrew.com

 

[kh54s10]

The most common reason for poor mash efficiency is the grain crush. Too coarse, and you end up with a low OG. I had this problem quite a bit with my LHBS mill. I got myself a corona mill, and my efficiency went way up. (Note, the corona mill also made brew day a bit more tedious, as you get quite a work out milling 12 lbs of grain!).

The 90-minute mash and temperature drop did not cause the low OG. Nor did the mashout problem.

I suggest you read Denny Conn's method for batch sparging: www.dennybrew.com

I used a Corona style mill for years... get a bolt the right size to replace the one in the handle and attach an electric drill. It was not much more difficult than with my new Cereal Killer mill. I didn't even hand crank a full batch. I started to and got the drill after about one pound of the first batch.

 

[GoeHaarden]

Welcome.

Are you sure your thermometers are accurate? Like @kh54s10 said 180 strike water seems pretty high. With most conversion happening in the first 5 minutes you could have zapped a lot of your enzymes.

I'll echo the others regarding crush being important.

Also, what about water chemistry? Water can have a big impact on everything in all-grain.

Posting your recipe would help as well...

Cheers!

 

[BurningMountainBrewer]

Several things to note.

Is your grain very cold when adding to the mash? I only need the strike water to be about 168 - 170 degrees to get a mash at 154. Try pre heating your mash tun.

The extra time for the mash should not be much of a concern.

Nor would be the drop in temperature.

Are you fly sparging or batch sparging? If batch sparging you can skip the mash out. You go from mash to boil quickly enough there is no need to stop the action with a mashout. In the short time there will not be much difference as there would be with an hour long fly sparge.

Add the sparge water, then stir very thoroughly to get as much residual sugar into solution as possible. The vorlauf and drain.

It has also been shown that sparge water temperature is not critical. I have done a few where I just sparged with the heat remaining in the HLT water.

Low OG is most often traced back to a poor crush. Were the grains milled well, that all the grains were cracked open?

Thanks for the questions to help me figure this out. Grains are kept at room temperature (about 65 degrees). I'm batch sparging. When I added it to the mash I stirred it in pretty thoroughly. We crush our own grains with a grain mill (2 rollers). We have them set at a little more than a credit card thick. The grains seemed to be well crushed, no intact hulls but also not alot of powder.

 

[kh54s10]

Thanks for the questions to help me figure this out. Grains are kept at room temperature (about 65 degrees). I'm batch sparging. When I added it to the mash I stirred it in pretty thoroughly. We crush our own grains with a grain mill (2 rollers). We have them set at a little more than a credit card thick. The grains seemed to be well crushed, no intact hulls but also not alot of powder.

Try tightening it up a little.

 

[Gnomebrewer]

What efficiency was 1.065 based on? 1.050 might not be that bad.
Part of your issue may also have been a lack of stirring - a few thorough stirs throughout the mash helps.
WRT the crush, even with a poor crush, you can get 100% conversion efficiency if you mash for long enough (providing there aren't whole/uncrushed grains), but it takes longer than with a fine crush. Braukaiser's efficiency calculator has a section for calculating conversion efficiency - you should continue mashing until you reach at least 90% - a higher temperature rest (around 160) can help.

 

[Ralphie0523]

I collected 6 gallons of wort. Though I could have collected more, I stopped at 6 gallons. The rest of the process went smoothly and I ended up with 5 gallons of brew to ferment. When I tested the gravity, it was 1.050. The target was 1.065.

So, there were several issues with this brew and I'm wondering which (if any) may have caused the lower than expected gravity reading. Thanks for your patience with this long post!

This part stuck out to me. Collecting more Could possibly mean you used more water than needed in the sparge. When I started I had to really take a few (5-7) batches to dial in process and understand my sparge techniques. I would propose it is possible you oversparged in combination with the fact the mash sat with no circulation or stirring for 90mins.

I also want to echo the comment of basing your OG on what? Was this calculated from brew software? Have you had similar efficiencies from your previous two batches and this is an outlier? If you got the recipe from somewhere you may have a different efficiency than that posted recipe and have to adjust.

 

[kh54s10]

This part stuck out to me. Collecting more Could possibly mean you used more water than needed in the sparge. When I started I had to really take a few (5-7) batches to dial in process and understand my sparge techniques. I would propose it is possible you oversparged in combination with the fact the mash sat with no circulation or stirring for 90mins.

I also want to echo the comment of basing your OG on what? Was this calculated from brew software? Have you had similar efficiencies from your previous two batches and this is an outlier? If you got the recipe from somewhere you may have a different efficiency than that posted recipe and have to adjust.

IMO, leftover sparge water could cause a bit of a hit but I don't think that much. And stirring should have only a tiny bit of gain in OG. I rarely stir during the mash and get very little if any difference when I do.

And yes, the source of the target OG would tell a lot. The OG that was obtained might actually be spot on to what could have been gotten.

 

[BurningMountainBrewer]

Thanks for all of the comments and suggestions. I'm using BrewGR to do my recipe calculations. Plugging in my fermentables (8 lbs 2-Row Malt, 2 lbs Caramel/Crystal 20, 2 lbs Carapils) I got an OG of 1.065. In my previous brew I used the same grains and got an OG of 1.065 on the nose. So something was definitely off this time. We did adjust the rollers slightly on the grain mill, so I'm thinking perhaps that was the issue. I'm going to try tightening them up slightly next time and see if that makes a difference.

It is also entirely possible I'm using too much water for the sparge process. I followed the formula of 1/2 gallon per pound of grains (6 gallons of sparge water). The whole sparge process is stretching my brain a bit.

 

[kh54s10]

Batch sparging is super simple.

Vorlauf and drain the mash tun.

Then measure what is in the boil kettle. I made a dip stick by adding a gallon, making a mark on the stick, (carved into the edge) added another gallon, another mark etc. I have a double mark at the point I know I need for preboil volume.

You now know how much more water you need to get to preboil. I do 1/2 then measure again just to be a little more accurate. This way I leave very little water in the grains.

 

[sicktght311]

https://www.morebeer.com/content/sparge_water_calculator

I've been using this since the day i started using my 3v herms system. The volumes the calculator puts out have never failed me, and i use it to calculate every new recipe. Just adjust variables such as trub and equipment loss, as well as boil off rate based on your system, and hit calculate! For a mostly malt centric beer i use 1.3-1.4 for my mash thickness. If its something like a NEIPA or Cream ale with a lot of flaked adjuncts, i use more towards 1.5-1.6.

 

[Ralphie0523]

IMO, leftover sparge water could cause a bit of a hit but I don't think that much. And stirring should have only a tiny bit of gain in OG. I rarely stir during the mash and get very little if any difference when I do.

And yes, the source of the target OG would tell a lot. The OG that was obtained might actually be spot on to what could have been gotten.

Agreed that it isn’t the sole cause, but my experience with mashing/sparging is every little thing counts.

So something was definitely off this time. We did adjust the rollers slightly on the grain mill, so I'm thinking perhaps that was the issue. I'm going to try tightening them up slightly next time and see if that makes a difference.

It is also entirely possible I'm using too much water for the sparge process. I followed the formula of 1/2 gallon per pound of grains (6 gallons of sparge water). The whole sparge process is stretching my brain a bit.

Echo the others’ advice to get your volumes for sparges worked out. This helps a lot, even if you sacrifice efficiency for getting the volumes right on a single batch, it is only one batch and you know it until you change your equipment.

Crush is also a big factor, so good you know to look there as well. Best of luck going forward and hope you continue to grow and enjoy all grain!