Looking for help on improving my attenuation

[rdavidw]

I have been brewing for a while and overall happy with how my beer is coming out but seem to regularly end up with higher than desired final gravity levels.

It seems to be almost all of my beers but I will use this Hop Head Kit as an example.

My first thought is that I am under pitching my yeast. I make a 2L starter in a temp controlled stir plate and let it go for about two days at the recommended temp for that yeast. I used WLP005 British Ale Yeast for the Hop Head and kept it at 66F. I then turn off the stir plate, remove the stir bar, and drop the temp down to 38F for about six hours. After all of the yeast has settled to the bottom I decant all but a little bit of the wort stir it back up and let it warm up to around 70F before pitching it. Seemed to be a sizable amount of yeast.

My second thought is my mash temp is too high. I have a single induction burner with two pumps and three 10 gallon kettles. I have a built-in copper coil in my brew kettle and start by heating 9.5 gallons of strike water to 160F. I added two extra pounds of two row and .6 pounds of acid malt for a total grain bill of 18.1 pounds. I pump 5.8 gallons of the strike water through the coil to my mash tun and then set up one pump recalculating the wort through the coil in my brew kettle and the other pump is whirl pooling the water in brew kettle. Basically, my brew kettle is my hot liquor tank until I sparge. After I add my grains and stirred them in well I turn on the pumps and the burner. My mash starts out around 120F and I bring it up to 152F and am careful not to go over. I have good thermometers in my kettles have checked them with a temp probe.

Here is where I may be causing problems. In order to bring my mash temps up faster, I have been overshooting my hot liquor tank temps and then turning off my burner and letting them settle at my target. For example, my mash started out at 120F and I want it at 152F. I will bring my HLT up to about 177F and then turn of the burner. The MT will climb up to 152F and the HLT will drop to 154F and then I turn the burner on low to keep at that temp for about an hour. If it looks like I may go over the 152F in the MT then I can pull the lid off of the HLT and if the temps are still going up I can turn the wort pump off until the temps come down. Even thought my MT thermometer never went over 152F I am wondering if the wort temp coming out of the HLT coil is much hotter and causing my attenuation problems?

After the hour I bring the water in my BK/HLT up to 180F and the temp in my MT to 168F. I then pump my sparge water thought the coil in the BK into my HLT. From there its pumped to the MT with an auto-sparge and the wort is pumped to the BK and I start to boil. I believe the 180F sparge water is hitting the mash at about 172F.

I am typically getting about 88% efficiency with smaller grain bills. With this larger grain bill I hit a 1.095 gravity at 5.5 gallons for a 79.2% efficiency. My target final gravity is 1.025 for an abv of 9.2. I cooled the wort to 66F and aerated well with a wine degassing stir on a drill. I keep the temp in the fermenter at 66F for the first week and then upped it to 68F for a second week. I then pitched dry champaign yeast and brought the temps up to 70F and held it there for two more weeks. After the month in the primary my gravity is still at 1.036. I just racked it on the hops and will then cold crash it and keg in two weeks. There was still some airlock activity before I racked it but the gravity readings were not falling very much.

Here is my fermenter temps setup:Glycol Temp Control Set Up

Thanks in advance for any suggestions.

 

[jekeane]

I'm having a bit of a hard time following the path of your recirculation. is your herms coil in the 177° pot? If it is I suspect that is a problem. The bulk of conversion happens pretty quickly and if you are running a large portion of your mash through the herms at 177° you could be setting yourself up for a less fermentable wort.

 

[rdavidw]

I'm having a bit of a hard time following the path of your recirculation. is your herms coil in the 177° pot? If it is I suspect that is a problem. The bulk of conversion happens pretty quickly and if you are running a large portion of your mash through the herms at 177° you could be setting yourself up for a less fermentable wort.

That is correct Jekeane. I have been recirculating my mash through my herms coil that was in 177F water. I thought I was safe because the thermometer on my mash tun never went over 152F. I agree with you that is likely the culprit. In the future I am going to run it more like Kal's Electric Brewery. He has the temp prob in the HLT and keeps his HLT at or a degree or two above the target mash temp. I will do the same thing from now on. I will keep the water in my HLT at 154F and just wait a little longer for the temp in the MT to come up to 152F.

My set up is a little confusing but it works well for me:

Rather than needing to clean two coils and have two separate burners, I heat all of my water in my "brew kettle" on the right. Here is the inside of my brew kettle:

It functions the same as a traditional herms hot liquor tank up until the start of the sparge. Once I have hit my mash out temp and sparge water temp. I pump all of the sparge water over to my HLT on the left that has no coil in it. It only takes three or four min to pump the water over. The built in coil BK does not interfere with the boil or hops spider. I clean my MT after the sparge is done and slide my empty HLT next to my BK and fill it with about 6 gallons of ice blocks and cold water. I cool my wort in under 15 min and don't waste any water. I whirlpool my wort with one of the pumps and drain the first 4 gallons of the ice water slowly through the coil into a bucket for my hot clean up water. I then add a few gallons of cold tap water to my HLT and use the second pump to recirculate the ice water through the BK coil till I hit my target temp. I re-freeze the water left in the HLT for the next time I brew.

Thanks again for the help!

 

[bigdaddybrew]

I think you may be denaturing a significant amount of the mash enzymes as it is recirculated through the 177f tank as it raises the mash tem from 120f. You might try mashing in with hotter strike water to hit 148f and use your recirculating system to maintain it at 148f for 60 min. Also you're using a lower attentuating yeast. Try Nottingham. It's more aggressive at finishing beers and may result in a lower terminal gravity especially on these bigger beers.

 

[Dcpcooks]

I use a herms coil for my brews but I do not ramp as aggressively (or in the same manner) as you do. I think it is critical that you monitor the temp of the wort returning to your mash tun. If your mash is at 120 and you run the wort through a coil at 177 degrees you have denatured some of the enzymes in that portion of the wort. So a portion of your early recirculated wort may not be converting to fermentable sugars but rather longer chain sugars that can't be converted by brewers yeast or denatured completely and can't be converted. Most of your fermentable sugars come from alpha and beta rests between 144-158. Since your already at 177 your denaturing your enzymes before you have complete conversion on a percentage of your mash. It would be a a difficult calculation to perform as it's based on volume and flow rate but I'd estimate that it takes about 20 min to see your hlt temp drop into the low 150 range. So as a guess your denaturing somewhere around 20-30% of your enzymes.

I don't think you need to ramp through this large of a range unless you are using a large percentage of unmalted wheat. A protein rest and a beta gluc rest have their place but you don't need them for the majority of beers. Be selective.

You can try a few things to isolate the problem.

Install a tee and add a thermometer after your herms coil before it returns to the mash. Then you'll know what your wort temp actually is. I control my hlt and wort by this method. I don't worry much about the mash bed temp I monitor the wort temps. Heat your wort correctly and your mash bed will follow. The rate of change in your mash bed will be determined by flow rate and the amount of energy applied to the mass of your grain bed. But it's the wort temp you really need to be concerned with at every stage of your ramps.

Ramp your hlt more slowly and recirculate at the same time. Don't shoot for 177, shoot for 3-4 degrees above your next rest. So mimic the mash rests you want with the hlt ramps. You say above your careful not to go over 152 when in reality a portion of your wort has been at 172-173 for a portion of the time. The mash hasn't been over temp but your wort has. Remember that a portion of your sugars and your enzymes are free floating in the wort.

Do a simple smash batch to test it out. Infuse at 144-148 rest it for 20 min and then apply heat to your coil and ramp to 153 or even as high as158. Let it rest for 30 min and then ramp to mash out temps and go to the kettle. Do this with a recipe you've had trouble with and compare the end results.

Use a yeast calculator to estimate pitch size so you know you have enough yeast.

Crash your starter a day before and let it sit over night. You may be selectively pressuring your yeast if you don't give it enough time to drop the least flocculant yeast. Those are the yeasts that may help you complete fermentation. I think this is low on the scale of reasons but 6 hour crash is a little fast.

Slow everything down. If you really need a fast brew day use a single infusion at 152 for 45 min and test for conversion.

Since you have a heated stir plate you can perform a limit of attenuation test. Pull a sample of your wort after you pitch the yeast and put it on your stir plate at 75-80 degrees. Spin it for a few days and check the final gravity. This will be the maximum level of attenuation you can hope for. Your main batch may not hit that max level but at least you will know the best possible performance you could achieve.

Try getting pure o2 for aeration. Higher gravity beers will benefit from higher levels of o2 in the wort. You are not getting enough pure 02 by stirring. Again this is not the main cause but it's a small thing that can help you get a better fermentation. The book on yeast has a nice section on o2 levels achieved by different methods.

Wait until your gravity reading is stable before you rack your beer.

Champagne yeast can finish a high gravity beer because it can ferment longer chain sugars and it's alcohol tolerant. I think the fact that champagne yeast can't finish fermenting your beer is a strong indicator that your creating longer chain sugars in the mash with your process.

If you can't ramp fast enough with your induction burner then you need more power, a larger coil a different method or a combination of the all of those.

Hope this helps you generate a few ideas.

Cheers.

 

[kh54s10]

I have been brewing for a while and overall happy with how my beer is coming out but seem to regularly end up with higher than desired final gravity levels.

It seems to be almost all of my beers but I will use this Hop Head Kit as an example.

My first thought is that I am under pitching my yeast. I make a 2L starter in a temp controlled stir plate and let it go for about two days at the recommended temp for that yeast. I used WLP005 British Ale Yeast for the Hop Head and kept it at 66F. I then turn off the stir plate, remove the stir bar, and drop the temp down to 38F for about six hours. After all of the yeast has settled to the bottom I decant all but a little bit of the wort stir it back up and let it warm up to around 70F before pitching it. Seemed to be a sizable amount of yeast.

Try running your starter at room temperature. The yeast really do better in warmer temperatures. It is just not good for the flavor of your beer. Cool longer before you decant. Make sure the starter wort is very clear, otherwise you are pouring away a significant amount of yeast cells.

My second thought is my mash temp is too high. I have a single induction burner with two pumps and three 10 gallon kettles. I have a built-in copper coil in my brew kettle and start by heating 9.5 gallons of strike water to 160F. I added two extra pounds of two row and .6 pounds of acid malt for a total grain bill of 18.1 pounds. I pump 5.8 gallons of the strike water through the coil to my mash tun and then set up one pump recalculating the wort through the coil in my brew kettle and the other pump is whirl pooling the water in brew kettle. Basically, my brew kettle is my hot liquor tank until I sparge. After I add my grains and stirred them in well I turn on the pumps and the burner. My mash starts out around 120F and I bring it up to 152F and am careful not to go over. I have good thermometers in my kettles have checked them with a temp probe.

I am not sure exactly what this really means, but I would work to have your mash temperature correct right after you have stirred the grains thoroughly, then keep it steady at the right temperature. I do pale ales 148-150, Ambers and similar 150 - 152. Porters and Stouts 151 -154.

Here is where I may be causing problems. In order to bring my mash temps up faster, I have been overshooting my hot liquor tank temps and then turning off my burner and letting them settle at my target. For example, my mash started out at 120F and I want it at 152F. I will bring my HLT up to about 177F and then turn of the burner. The MT will climb up to 152F and the HLT will drop to 154F and then I turn the burner on low to keep at that temp for about an hour. If it looks like I may go over the 152F in the MT then I can pull the lid off of the HLT and if the temps are still going up I can turn the wort pump off until the temps come down. Even thought my MT thermometer never went over 152F I am wondering if the wort temp coming out of the HLT coil is much hotter and causing my attenuation problems?

Again, calculate your strike temperature so that you reach the (152 degrees) as soon as the grains are stirred in. Then just keep the temperature steady with the re-circulation.

After the hour I bring the water in my BK/HLT up to 180F and the temp in my MT to 168F. I then pump my sparge water thought the coil in the BK into my HLT. From there its pumped to the MT with an auto-sparge and the wort is pumped to the BK and I start to boil. I believe the 180F sparge water is hitting the mash at about 172F.

Get the mash itself to 170 degrees for mash out, then sparge. You do not really care what the temperature of the water is.

I am typically getting about 88% efficiency with smaller grain bills. With this larger grain bill I hit a 1.095 gravity at 5.5 gallons for a 79.2% efficiency. My target final gravity is 1.025 for an abv of 9.2. I cooled the wort to 66F and aerated well with a wine degassing stir on a drill. I keep the temp in the fermenter at 66F for the first week and then upped it to 68F for a second week. I then pitched dry champaign yeast and brought the temps up to 70F and held it there for two more weeks. After the month in the primary my gravity is still at 1.036. I just racked it on the hops and will then cold crash it and keg in two weeks. There was still some airlock activity before I racked it but the gravity readings were not falling very much.

Is the drop from 1.095 to 1.036 in line with the attenuation that the yeast can do? Though the champagne yeast should have taken it much lower.

Here is my fermenter temps setup:Glycol Temp Control Set Up

Thanks in advance for any suggestions.

I see a possibility of under pitching, even with the starter for reasons stated.

I see a low mash temperature but that should give you a lower FG not higher.

Check the calibration on your hydrometer. (you aren't measuring FG with a refractometer are you? - if so you need to correct for the presence of alcohol.) The hydrometer should read 1.000 in distilled water.

 

[rdavidw]

I use a herms coil for my brews but I do not ramp as aggressively (or in the same manner) as you do. . . . .

Wow Dcpcooks, I think you nailed it. I just ordered this Inline Thermometer and think that will be very helpful!

I will also crash my starter the day before I brew and look into getting pure o2 for aeration. Thank you so much; very helpful.

I see a possibility of under pitching, even with the starter for reasons stated.

I see a low mash temperature but that should give you a lower FG not higher.

Check the calibration on your hydrometer. (you aren't measuring FG with a refractometer are you? - if so you need to correct for the presence of alcohol.) The hydrometer should read 1.000 in distilled water.

Thank you kh54s10. The drop from 1.095 to 1.036 is not in line with the attenuation, especially with the re-pitch of the champagne yest. I think I can only do so much with this batch but I should still be drinkable. Its a very hop heavy beer which should offset the extra sugar some. I suspect my next batch will not have the same problem.

My hydrometer is good. I use a refractometer for my wort but then a small glass hydrometer for my beer. Checks out at 1.000 in OR water.

Thanks again!

 

[rdavidw]

Try getting pure o2 for aeration. Higher gravity beers will benefit from higher levels of o2 in the wort. You are not getting enough pure 02 by stirring. Again this is not the main cause but it's a small thing that can help you get a better fermentation. The book on yeast has a nice section on o2 levels achieved by different methods.

Is this a good choice for pure o2 aeration? More Beer OxyWand

Would that work well with a Home Depot 1.4 Disposable o2 tank?

Run it for 30 seconds or so?

 

[Dcpcooks]

Is this a good choice for pure o2 aeration? More Beer OxyWand

Would that work well with a Home Depot 1.4 Disposable o2 tank?

Run it for 30 seconds or so?

Those will work. It was my first unit. I ran it about a min at the low end of pressure.

Your thermometer will do the job as well!

Cheers!

 

[rdavidw]

Those will work. It was my first unit. I ran it about a min at the low end of pressure.

Your thermometer will do the job as well!

Cheers!

I will run it for one min or so. Any danger running pure o2 in my indoor basement setup? I'm all electric so there is no flame from my brewery but I do have a gas furnace with a pilot flame about 25 feet away. I have a strong hood vent so I should be ok?

 

[bigdaddybrew]

If you pointed the tip right into the furnace it would make the flame burn hotter otherwise not a real danger.

 

[rdavidw]

If you pointed the tip right into the furnace it would make the flame burn hotter otherwise not a real danger.

Fantastic! Glad to hear that. Thanks

 

[rdavidw]

OK - Everything is making sense now. My MT Blickman Brewmometer is running a full 9 degrees cold. When I thought I was holding at 152F I was actually mashing at 161F. No wonder my FG is staying so high. I tested all of my thermometers with a digital prob back when I got my set up about five years ago or so. I brew about once a month and started having problems with my FG about four or five batches ago. The Thermometer must have been going slowly bad over the last six months or so.

I just made a Sam Adams Clone and was able to hold the mash at the correct temp. I also opened the gap in my grain mill from 0.03" to 0.045" per Kal's recommendation. I have been typically hitting a brew house efficiency of 88% with lager gain bills coming in a little lower. When my thermometer was broken it dropped a little. With the correct temps and the more coarse grain crush, I just hit a 94.8% efficiency on the Sam Adams clone. :rockin: Kal knows what he is doing!

I am going to throw my Blickman Brewmometer in the trash and replace it with a Thermowell and a Inkbird Controller. I am using a 3500 Watt Induction Burner that runs on 220 and will not work on the controller. Instead I will run the HERMS pump on the controller as a safety in case my HLT temps get too high the pump will kick off and the mash temps will no longer rise.

Thanks for everyone's help with this.

 

[bigdaddybrew]

Doesn't the Blichman brewmometer have an nut to adjust it's set point?

 

[rdavidw]

Doesn't the Blichman brewmometer have an nut to adjust it's set point?

Yes - but it seem to be off more at higher temps, for example, at room temp, its off by about 5 degrees but at around 150F its off by about 9 degrees. Chucking it is a cheap fix. I do like the brew markings but I like having an accurate thermometer a lot more.