The Same Low OG Twice in A Row (A Detailed Post for You)

[BeeSpojj]

Hello all!

I have finally been able to get into brewing (been waiting to for a while but haven't had the time) and I have now completed two of my own simple Blonde Ale recipes. However, things started out rough in my first batch but ended up better in the second. The problem is that both batches have had a very low OG of 1.030 instead of the target 1.047. Exact same OG for both batches even after adjusting my BeerSmith profiles for the second batch. I've searched the web and looked at a bunch of forums here and couldn't figure out a definitive answer. So, here are the details and I hope you can help pinpoint where I'm going wrong. I'm sorry for the long post, but every thread I read was very short and it seemed solutions were hard to make with little info, so hopefully this will make it more painless.

The BeerSmith recipe is also attached if you would like to see where things are at (Name is Cat & Carrot in BeerSmith).

Brewing equipment:

-8 gallon Alfred brewing pot

-11.7 gallon Mash King mash tun with a 12'' bazooka tube (I have a false bottom but there would be way too much dead space if I'm brewing small batches)

-Secura 8100MC 1800W induction cooktop (used this in a brewing class and it did the trick, and I'm only brewing small batches for now. I would grab a propane burner for larger batches.)

-Grains are milled at the store when they are purchased.

-Brewers Best pH strips (I don't trust these. pH meter is the next purchase)

-Hydrometer calibrated for 68F


Attached below are my current BeerSmith equipment profile settings (adjusted after the two batches, sorry I can't accurately recall what they were before but I can ballpark it if need be):

I create my recipes as if they were 5gal batches and simply scale them down.

Recipes were followed by the Brew Steps tab.


Attempt 1:

Recipe:

-3.3lbs Bohemian pilsner
-1.11lbs pale Canadian 2 row
-0.75lbs honey malt

Process (All volumes/temps given/estimated by BeerSmith):

-Hit strike temp, added 6.11L of water and threw the grains slowly in and stirred well. This dropped the mash temp lower than I was expecting to 136.4F, so I added another 1L of water at 194F but this only raised the temp to 140F. So already I was mashing with way too low of a temperature. After 10 minutes I checked the pH, pH was estimated to be 5.72 with my water profile (so I would add lactic acid) but my pH strips were measuring at about 5 (how is this possible?). I tried adding baking soda to raise it (about a teaspoon) and my strip read 6.4. So I added acid and it went right back down to 5 on the strip. It was a mess, so I gave up and just let the mash go.

-Mashed for 75mins, mashed out for 10mins with 2.9L of 194F water.

-Fly sparged with 16.7L of 170F water. I sparged way too quickly, let the grain bed dry out a few times.

-Pre-boil gravity was 1.028 (I mixed the wort in the kettle to get an accurate reading and took the measurement at 68F).

-Estimated pre-boil was 24.08L. Boiled for 60 minutes (started the timer when I had a low rolling boil). Boiled off about a gallon, ended with 20.2L (estimated 17.27L) after chilling. Lost 1 gallon to trub.

-Measured OG at 68F and had a reading of 1.030 (target 1.047).

For this attempt, I had a mash efficiency of 106% in BeerSmith, so obviously something was wrong in my profiles. Mash efficiency was set to 70%.


Attempt 2 (learned from my mistakes):

Recipe:

-3.5lbs German Pilsner
-1.15 Canadian 2 row
-0.6lbs honey malt

Process (All volumes/temps given/estimated by BeerSmith):

-Hit strike temp, added 6.15L of water, poured grain in slowly and stirred well. Mash temp was on target at 147.2F. After 10 minutes I checked the pH (estimated 5.74) and the strips read 5. There is no way it would drop this low, hence why I don't trust the strips. Based on this reading, I didn't bother adding anything this time and just left it. I let the mash go for 75 minutes. Mashed out for 10 minutes with 4L of 205F water.

-Fly sparged with 16.5L of 170F water. Sparging went really well, kept about 2.5cm above the grain bed the whole time, used a plastic strainer to disperse water and avoid tunneling, sparged with a good rate of water in = water out. (took about 40 minutes)

-Pre-boil gravity was 1.030 at 68F.

-Pre-boil volume was 23.94L. Boiled for 90mins, boiled off 1 gallon. Ended with 20.1L after chilling when it was supposed to be 15.51L. After seeing this I changed the boil-off to 1 gallon in BeerSmith.

-Measured OG at 68F and had a reading of 1.030 (target 1.047).

Luckily this time I had some DME in case this happened, so I managed to save this batch but I definitely don't want to have to do this every time. .

Efficiency was still set at 70%, mash efficiency was at 95.7% so something is still off because there is no way I'm even able to come close to that with my set up.


I can only think of two possibilities that might be contributing to the low OG:

1. The pH in the mash was actually too low. However, I have no idea how this is possible or how I would be able to change that other than doing custom water chemistry (I would rather not for the time being until things start to go well). Beersmith has a predicted pH of 5.7 with my water profile and grain bill (obviously did not get that if the strips are accurate). Again, this was with zero additions to try to change the pH. Before brewing, I take my total water + extra and bring it to a boil to get rid of any chlorine that may be in it.
2. I had my boil off set to 2 gallons when I actually only boiled off 1 gallon. I changed this after the fact and my recipe was altered by a few liters less so I doubt this would have a terribly large impact. Or would that small difference actually dilute the wort that much? In my second batch I had an extra 5L of wort so did that throw it off?

If anyone has any suggestions as to what might be going wrong I would greatly appreciate it. Again, my apologies for the long read, but I hope I provided enough detail for some conclusions to be made. Thank you for your time!


On the bright side, the first batch is now done fermenting and other than the weak alcohol content, the flavour, colour and clarity have all come out perfectly so far!


Cheers,
Brandon

 

[CameronK]

I've had lots of efficiency issues when using the LHBS mill. My efficiency went way up (from ~50% efficiency to 81%) when I did a BIAB batch with a triple crush. Definitely grab a handful of your milled grain and compare to some online images of good crushes.

Next, I'd really try brewing a batch with RO or distilled water. If your pH measurement isn't spot on, it's much easier to start from a blank slate and add the water additions that the calculators recommend.

 

[BeeSpojj]

I've had lots of efficiency issues when using the LHBS mill. My efficiency went way up (from ~50% efficiency to 81%) when I did a BIAB batch with a triple crush. Definitely grab a handful of your milled grain and compare to some online images of good crushes.

Next, I'd really try brewing a batch with RO or distilled water. If your pH measurement isn't spot on, it's much easier to start from a blank slate and add the water additions that the calculators recommend.

Here is the quality of the crush. And thank you for the advice. If it comes down to it I'll probably have to use distilled water, it would just be a bit of a hassle since my area already has the ideal water profile for the beer styles I'm interested in brewing. As of now since I'm just starting out, I'm trying to avoid having to do custom water chemistry until I absolutely have to.

 

[RM-MN]

-Grains are milled at the store when they are purchased.

I was going to say that the store usually mill grains too coarse for good conversion efficiency. After seeing your photos I'm sure of it. You can do some compensation by mashing longer but it is limited. Getting your own mill is the only real solution.

-Brewers Best pH strips (I don't trust these. pH meter is the next purchase)

I'd put off this purchase. It is of limited usefulness unless you have really bad water and get a really expensive meter.

 

[Immocles]

-Pre-boil gravity was 1.030 at 68F.

-Pre-boil volume was 23.94L. Boiled for 90mins, boiled off 1 gallon. Ended with 20.1L after chilling when it was supposed to be 15.51L. After seeing this I changed the boil-off to 1 gallon in BeerSmith.

-Measured OG at 68F and had a reading of 1.030 (target 1.047).

Unless I'm completely missing something (which is known to happen, quite often. Ask my wife.), I don't see how it would be possible to have the same gravity pre and post boil when you're boiling off a gallon of wort?

 

[BeeSpojj]

Unless I'm completely missing something (which is known to happen, quite often. Ask my wife.), I don't see how it would be possible to have the same gravity pre and post boil when you're boiling off a gallon of wort?

That's what's puzzling me, I'm not sure what I'm missing either. Hydrometer readings have been taken at the proper temps. Hydrometer has no cracks and worked just fine when I was adding DME so it don't think it was a misread on my part.

 

[McKnuckle]

Pre-boil gravity is notoriously difficult to accurately measure, so that is your issue w.r.t. the equivalent readings. Equivalent pre- and post-boil gravity is impossible. So it means the pre-boil wort was not adequately mixed, and the actual reading was lower.

If you are sure of your volume measurements, and the post-boil SG was 1.030, then you can calculate the pre-boil SG using this calculator. It would have been ~1.025.

 

[Carolina_Matt]

That's what's puzzling me, I'm not sure what I'm missing either. Hydrometer readings have been taken at the proper temps. Hydrometer has no cracks and worked just fine when I was adding DME so it don't think it was a misread on my part.

What's your process for taking pre-boil gravity? If you're just taking a small sample and leaving it uncovered while it chills, it's possible that some of it is evaporating (which would make it more concentrated and artificially increase the gravity).

 

[BeeSpojj]

Pre-boil gravity is notoriously difficult to accurately measure, so that is your issue w.r.t. the equivalent readings. Equivalent pre- and post-boil gravity is impossible. So it means the pre-boil wort was not adequately mixed, and the actual reading was lower.

If you are sure of your volume measurements, and the post-boil SG was 1.030, then you can calculate the pre-boil SG using this calculator. It would have been ~1.025.

So say it was actually 1.025 and the sample was poorly mixed, would having that extra 1.3 gallons at the end of the boil likely be the main part of the problem? If so, would my updated equipment profile and boil off volumes (screenshot above) likely be the solution? (aside from a possibly bad crush?)

 

[BeeSpojj]

What's your process for taking pre-boil gravity? If you're just taking a small sample and leaving it uncovered while it chills, it's possible that some of it is evaporating (which would make it more concentrated and artificially increase the gravity).

Process would be, stirring the wort in the kettle, filling the hydrometer tube with a sample, putting in the fridge to cool to 60F.

 

[McKnuckle]

Let's review some of the details.

You used 5.25 lbs of grain. For water, you state:
"Hit strike temp, added 6.15L of water"
"Fly sparged with 16.5L of 170F water"
"Mashed out for 10 minutes with 4L of 205F water"
"Pre-boil volume was 23.94L"

You used 26.65L of water, just about 7 gallons. Given an average absorption rate of 0.12 gal/lb, you would have absorbed 0.63 gallons during the mash, ending up with 6.37 gallons (24.11L) for pre-boil. You must have left a little more in the mash tun.

A one gallon boil-off would have gotten you to 5.37 gallons (20.33L).

I plugged all of this into my own reliable spreadsheet. I won't bore you with all the details. But bottom line, I come up with the SAME gravity numbers, both pre- and post-boil. However, here's the kicker: The efficiency is quite high. I get 95% conversion, 83% mash, and 82% brewhouse.

The bottom line is that you did very well with your process, but you used too much water for the grain weight; or conversely - if you got the right volume in your fermenter - you didn't use nearly enough grain. You got the gravity one would expect for your ingredients.

 

[BeeSpojj]

Let's review some of the details.

You used 5.25 lbs of grain. For water, you state:
"Hit strike temp, added 6.15L of water"
"Fly sparged with 16.5L of 170F water"
"Mashed out for 10 minutes with 4L of 205F water"
"Pre-boil volume was 23.94L"

You used 26.65L of water, just about 7 gallons. Given an average absorption rate of 0.12 gal/lb, you would have absorbed 0.63 gallons during the mash, ending up with 6.37 gallons (24.11L) for pre-boil. You must have left a little more in the mash tun.

A one gallon boil-off would have gotten you to 5.37 gallons (20.33L).

I plugged all of this into my own reliable spreadsheet. I won't bore you with all the details. But bottom line, I come up with the SAME gravity numbers, both pre- and post-boil. However, here's the kicker: The efficiency is quite high. I get 95% conversion, 83% mash, and 82% brewhouse.

The bottom line is that you did very well with your process, but you used too much water for the grain weight; or conversely - if you got the right volume in your fermenter - you didn't use nearly enough grain. You got the gravity one would expect for your ingredients.

Excellent, thank you for your response! So to clarify and make sure I understand, I should be using less water (as I've now set in my Beersmith profile shown in my original post) and possibly a little more grain and that should get me back into the realm of my target OG?

As for efficiency, how can I make that more accurate? I've seen the threads on how to calculate it manually, but Beersmith calculates it automatically so I'm not quite sure how I would go about adjusting it. Again, thank you for your time and response!

 

[McKnuckle]

I think you also need to be more critical of your Beersmith setup. Given the volumes you used, I thought you were making a 5 gallon batch. Yet your BS profile is showing a 10.9 liter batch. That's 2.88 gallons, not 5.

You say you're going to discard 2.8L / 0.74 gallons in the fermenter from a 2.88 gallon batch. Wow! That's a ton of loss. You should be wasting maybe a pint at most in a 2.8 gallon batch. That's only 0.125 gallons.

You have boil time set to 90 minutes, not 60. Then you are saying you'll boil off 3.8L / 1 gallon, but not at an hourly rate. So you will boil off one gallon in 90 minutes? That's an extremely low rate.

You're going to lose an entire gallon to trub in the kettle? That's a ton! You should be wasting maybe a cup, seriously. Dump everything but the hops in the fermenter.

This is just me, and a relatively small inaccuracy, but I hate the 4% shrinkage nonsense. It's only useful when you're measuring volumes by eye, looking at lines on a vessel. I ignore that and simply look at all volumes as normalized to room temperature.

All of these inaccuracies make Beersmith compensate by calculating that you need more water to start with.

 

[BeeSpojj]

I think you also need to be more critical of your Beersmith setup. Given the volumes you used, I thought you were making a 5 gallon batch. Yet your BS profile is showing a 10.9 liter batch. That's 2.88 gallons, not 5.

I had everything set up originally as a 5 gallon recipe. But since I am just starting out, I only wanted enough finished beer to fill 24 bottles (355mL). So I used the scale option to scale the recipe down. I currently have it set to fill 24 bottles (and a tad extra) based on what I've seen with my equipment. So to clarify, I am not making a full 5 gallon batch. I have just scaled a 5 gallon recipe to 10.90L (which is probably why the volumes were off in the first two batches).

You say you're going to discard 2.8L / 0.74 gallons in the fermenter from a 2.88 gallon batch. Wow! That's a ton of loss. You should be wasting maybe a pint at most in a 2.8 gallon batch. That's only 0.125 gallons.

This is still up for debate since I have yet to actually bottle a batch (the first one will be Friday) so that will be adjusted accordingly.

You have boil time set to 90 minutes, not 60. Then you are saying you'll boil off 3.8L / 1 gallon, but not at an hourly rate. So you will boil off one gallon in 90 minutes? That's an extremely low rate.

I thought that was low too. Its probably because I'm using an induction plate. The rolling boil is very much here and there, that's why I increased the time. I unchecked the hourly rate box because in the 90 minutes it was just over 1 gallon of boil off (6.5gal to 5.3gal). This low boil off also makes me think I had way too much water to start with since I did not come close to 15.5L

You're going to lose an entire gallon to trub in the kettle? That's a ton! You should be wasting maybe a cup, seriously. Dump everything but the hops in the fermenter.

After the boil and transferring to the fermenter, the trub was at about 0.8 gallons in the kettle (I used a whirlfloc tablet with 10mins left, but 0.8 may have been an overshot). So you're saying I should just open up that ball valve and let it go? On the second batch I tried to filter any trub that may have came out of the siphon through a nylon bag, so I would do that again to catch the hops. If I didn't filter like this however, wouldn't that greatly increase my loss to the fermenter? Also I thought you wanted to avoid transferring trub into the fermenter?


Also, side note: I had my doubts about my hydrometer, so I checked the calibration in 68F water. It read the second line below 1.000. So its calibrated to 1.004, meaning my gravities were actually about 1.026.

 

[McKnuckle]

To try and focus here, the first thing to do is to make your Beersmith volume inputs line up with reality. You've brewed a couple of times, so you have empirical data. Yes, you can change procedures like increase heat and boil off more, or filter out less kettle trub. But even if you don't change any procedures at all, your actual volume results are still not reflective of your Beersmith settings, and you have to correct that.

1.2 gallons evaporation in 90 minutes is 0.8 gallons/hr. So correct that value as well.

And yes, don't go nuts trying to filter out all the gunk from your kettle. The vast majority of it is NOT hops, and will settle to a tight layer on the bottom of the fermenter. Or at least, if you choose to filter, don't add water to compensate for a large loss. Post-boil losses are far less important to recipe accuracy. They only affect fermenter and packaging volume, not gravity. Gravity targets are hit by nailing the pre-boil and evaporation values.

How about a practical example?

Let's say you want a nominal 2.5 gallons in the fermenter, but a little more would be okay too. So let's shoot for a batch size of 2.75 gallons, which is a quart of losses on the cold side.

Moving backwards, you'll evaporate 1.2 gallons. Add that to your batch size. Now you need 3.95 gallons at the start of the boil, or after mashing to put it another way. If you use, say, 5.25 lbs of grain with an absorption rate of 0.12 gal/lb, that's 0.63 lost in the mash by absorption. Add that and now you're at 4.58 gallons of total water. Will you lose any wort in the mash tun that's not absorbed, such as from dead space that can't be drained? Add it here. This volume should be minimal to none in a small batch. There's always a way to collect it. So I'm going to ignore it in this example.

So now you have 4.58 gallons of water going into your recipe. Mash with half and sparge with half, mash will all of it (no sparge), or split it any way you like, but do not add any more water than this... and you will get much closer to your gravity estimate. Or at least, you will remove the volumes from the equation, and hone in on efficiency, which is a whole 'nother topic!

 

[BeeSpojj]

Perfect explanation. Thank you very much for your time, it is greatly appreciated!