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Old 10-02-2013, 02:11 PM   #1
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Default High gravity at end of sparge and always too-low OG

I know that "missing my OG" threads are abundant here but please help me figure out what I can do in my particular situation. I will list everything that I think needs improvement but I'm not exactly sure how I can do that.

I'm doing all-grain and mill the grain myself (I'm sure the grain crush can be improved but there must be more to my problem). I'm using a converted cooler mash tun and do batch sparging, all volumes and temps calculated with BeerSmith 2.0.

First off, I have NEVER hit my mash temperatures using the strike temps suggested by BS. This frequently results in a thinner mash because I have to add additional water (mostly boiling). My thermometer is accurate so that's not the reason. Guess I have to adjust my equipment profile for that.

Conversion is usually good after one hour as indicated by the iodine test. I do a Vorlauf until the wort is mostly clear and add it back to the mash. I then drain the wort into my brew kettle (but don't start the boil). I do batch sparging so I heat the water, dump it into the grain bed and stir it for a few minutes. I then let it sit for about 10 min so the grain bed can settle again. I repeat the Vorlauf and drain into the kettle once more.
And here's where my real problem lies: My OG is usually between 6 and 12 points low even with an efficiency adjusted to 68%. My pH at the end of the sparge is around 5.5 and the SG of the run-off is >5 Plato. My last brew started at 18.0 P pre-boil (should have been 19.9) but the larger volume (7 gal instead of 6.4) made up for this. However, the run-off, after 3.3 gal of sparging, was still 16 P! What can I do to recover the sugars in a smaller volume? Is it advisable to "recirculate" the sparge over the grains again? I have a pump and could do it but it would be more a "batch recirc" since I don't have any fly-sparging manifold.

Thanks for reading all this.

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Old 10-02-2013, 02:25 PM   #2
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I don't brew beers that are nearly as strong as you (if I'm reading this right, you were brewing a beer that was to have a preboil gravity of 1.083). You will always get lower efficiency with the higher gravity beers. There simply is not enough water to rinse all the sugars out. If I were you, I would simply adjust your efficiency settings down on BS to match what you are actually getting.

As for mash temps, are you preheating your mash tun? Fill the cooler with hot tap water and let it sit while you are bringing strike water to temp. This should help (or you could simply adjust the settings and raise the temp on your strike water).

I'm not sure what you mean by a "fly-sparging manifold". I fly sparge by simply by using my tubing (I try to wrap it into a loop so that the end is sitting about 1 inch above the water level). I regularly get better than 80% efficiency (although I am brewing beers with OGs around 1.050).

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Old 10-02-2013, 02:40 PM   #3
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Thanks for the suggestions. This high-gravity beer was based on the Imperial Vanilla Porter from Denny C.

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I don't brew beers that are nearly as strong as you (if I'm reading this right, you were brewing a beer that was to have a preboil gravity of 1.083). You will always get lower efficiency with the higher gravity beers. There simply is not enough water to rinse all the sugars out. If I were you, I would simply adjust your efficiency settings down on BS to match what you are actually getting.
According to BS my mash efficiency is 74.0% as to the predicted 74.8% so I'm almost spot on. I bet that if I took the time to confirm the boil-off rate and maybe another few equipment profile values I could nail my numbers better. Need to invest that time and propane I suppose


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As for mash temps, are you preheating your mash tun? Fill the cooler with hot tap water and let it sit while you are bringing strike water to temp. This should help (or you could simply adjust the settings and raise the temp on your strike water).
I tried both, pre-heating the mash tun or not and adjusting the temp in BS but it's always off by 4-5 °F. I also played around with the specific heat. I guess it's time for some more empirical data collection.

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I'm not sure what you mean by a "fly-sparging manifold". I fly sparge by simply by using my tubing (I try to wrap it into a loop so that the end is sitting about 1 inch above the water level). I regularly get better than 80% efficiency (although I am brewing beers with OGs around 1.050).
How does that work? I thought you'd have to be careful with channeling or is that more an effect of the lauter manifold (I use an SS hose)?
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Old 10-02-2013, 02:46 PM   #4
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My OG is usually between 6 and 12 points low even with an efficiency adjusted to 68%.
When are you measuring this...what's the sample from...stirred or not?
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Old 10-02-2013, 02:57 PM   #5
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When are you measuring this...what's the sample from...stirred or not?
Oh yeah, it's stirred alright! I put my 24" SS mash paddle to good use in the boil kettle I drained everything into the BK, stirred whirlpool-style, then took a sample from the top.
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Old 10-02-2013, 03:33 PM   #6
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Regarding Mash temps: I suggest you read jfowler's dough in process for hitting mash temperatures (posts 3 and 4). This is how I started and it really helped me get familiar with my system, and gave me the flexibility to ensure I hit my temperature every time. I've since been able to remove some of built-in insurance(s) but, for the most part, this is how I proceed on brewday. Water:grist ratios are not that important as long as it will fit in your MLT.
http://www.homebrewtalk.com/f36/do-n...1/#post2952574

Regarding missing sugars: If you know your crush needs to be adjusted then you need to adjust your crush - aside from your missing sugars. With a proper crush, you'll get better efficiency, and the sugars that you miss will mean a little bit less. HOWEVER, this doesn't mean that crush is your problem - just that you want your crush to be appropriate for your system and process.

You mash, you vorlauf, you drain your MLT. You fill your MLT, you stir, you vorlauf again?, you drain your MLT again. You're done. At the end of this you're efficiency in not good (sounds like 60% or less).

Stirring the primary runnings/mash. You didn't mention it so I will. Stir your initial mash, prior to draining, very well. Just like you do for your second runnings (1st batch sparge). Stir, stir, stir. Stir really well for a few minutes. Drain.

After stirring, I don't wait to drain - I start draining immediately; I'm not in a rush or anything, I just don't wait. I also don't drain my runnings at breakneck speed either - I drain at a moderate/moderate-slow pace. IMHO, this allows the runnings to filter down through your grainbed at about the same speed you're collecting the running in your BK which keeps the siphon from breaking. If you drain as fast as you can but the wort can't filter through the grainbed quick enough then air will find it's way through and break your siphon. Once you break your siphon, and you don't have enough wort left in your MLT you've basically lost some portion of your highest gravity wort. You'll attempt to get it back on your batch sparge but you'll only be getting a percentage of it, the remaining portion will be left for the compost/garbage. I have found this to be very system dependent. I find that wider-than-deeper MLT (15 gallon cube coolers) are more prone to this problem than deeper-than-wider MLT (igloo-like beverage coolers).

Given a certain amount of grain; a certain amount of strike water; a certain amount of grain absorption; a certain amount of dead space; you should know approximately how much your initial runnings should be by volume. On brew day, you should ensure that you're getting the running volumes you'd expect to get. I suspect that this is where you're running into problems - not getting out the expected amount of wort for each running, which just dilutes the gravity for the next running.

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Old 10-02-2013, 04:49 PM   #7
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Whoa, thanks for taking the time to write this reply!

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Originally Posted by stpug View Post
Regarding Mash temps: I suggest you read jfowler's dough in process for hitting mash temperatures (posts 3 and 4). This is how I started and it really helped me get familiar with my system, and gave me the flexibility to ensure I hit my temperature every time. I've since been able to remove some of built-in insurance(s) but, for the most part, this is how I proceed on brewday. Water:grist ratios are not that important as long as it will fit in your MLT.
http://www.homebrewtalk.com/f36/do-n...1/#post2952574
Thanks for the link; I actually did something similar last time but there's lots of room for improving my technique! I have a 70 qt cooler so space is not an issue.

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Regarding missing sugars: If you know your crush needs to be adjusted then you need to adjust your crush - aside from your missing sugars. With a proper crush, you'll get better efficiency, and the sugars that you miss will mean a little bit less. HOWEVER, this doesn't mean that crush is your problem - just that you want your crush to be appropriate for your system and process.
Well, I think my crush is not too bad since mash efficiency is almost perfect. I just hate the way I have to do the milling with my drill so I should say the process of crushing the grain is not the best but the results are decent.

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You mash, you vorlauf, you drain your MLT. You fill your MLT, you stir, you vorlauf again?, you drain your MLT again. You're done. At the end of this you're efficiency in not good (sounds like 60% or less).
Actually, my efficiency is usually around 65% but that's far from where I'd like to be (mainly because of all the money I put into my equipment ).

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Stirring the primary runnings/mash. You didn't mention it so I will. Stir your initial mash, prior to draining, very well. Just like you do for your second runnings (1st batch sparge). Stir, stir, stir. Stir really well for a few minutes. Drain.
Now that seems counter-intuitive. I thought I need to let the grains set so they form the bed for filtering. Wouldn't the stirring and then draining cause a lot of the small sediment to potentially clog the braid?

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After stirring, I don't wait to drain - I start draining immediately; I'm not in a rush or anything, I just don't wait. I also don't drain my runnings at breakneck speed either - I drain at a moderate/moderate-slow pace. IMHO, this allows the runnings to filter down through your grainbed at about the same speed you're collecting the running in your BK which keeps the siphon from breaking. If you drain as fast as you can but the wort can't filter through the grainbed quick enough then air will find it's way through and break your siphon. Once you break your siphon, and you don't have enough wort left in your MLT you've basically lost some portion of your highest gravity wort. You'll attempt to get it back on your batch sparge but you'll only be getting a percentage of it, the remaining portion will be left for the compost/garbage. I have found this to be very system dependent. I find that wider-than-deeper MLT (15 gallon cube coolers) are more prone to this problem than deeper-than-wider MLT (igloo-like beverage coolers).
Although I do start my drain very slowly to, as you said, set the bed correctly, I increase the flow after that. I think that's what Denny Conn states on his website:
Quote:
fter conversion, the sweet wort is recirculated as normal and the mashtun is completely drained as quickly as possible (NOTE:quick draining is a benefit, not a requirement, of batch sparging. I recommend you start the recirculation with the valve just cracked open, to set the grain bed correctly. After you return the vorlaufed portion to the mash tun, you can open the valve whatever amount works for your system), and an addition of sparge water is added. This is stirred into the mash, and after recirculation is once more drained as quickly as the system will allow.
However, I experienced a very slow drain with this wort so maybe what you described was part of my issue. I'll investigate that for sure

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Given a certain amount of grain; a certain amount of strike water; a certain amount of grain absorption; a certain amount of dead space; you should know approximately how much your initial runnings should be by volume. On brew day, you should ensure that you're getting the running volumes you'd expect to get. I suspect that this is where you're running into problems - not getting out the expected amount of wort for each running, which just dilutes the gravity for the next running.
Another great yet simple advice! I really have to convince the wife to allow me to brew a "NIST" beer - one that's solely intended to work out the specifics of my system. Something lighter like a blonde ale that she would even like if turns out good.
Again, many thanks for your very good argumentation St. Pug!
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Old 10-02-2013, 04:59 PM   #8
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How does that work? I thought you'd have to be careful with channeling or is that more an effect of the lauter manifold (I use an SS hose)?
Well, you should have an inch or two of water above the grain bed. In my experience, this protects the grain bed and prevents channeling as long as you have the sparge tube close enough to the liquid.
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Old 10-02-2013, 05:06 PM   #9
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According to BS my mash efficiency is 74.0% as to the predicted 74.8% so I'm almost spot on. I bet that if I took the time to confirm the boil-off rate and maybe another few equipment profile values I could nail my numbers better. Need to invest that time and propane I suppose
I am a bit confused. Are you hitting your OG but missing on preboil? Or are you having to boil for a very long time to hit your OG because your preboil is low? Unfortunately, I am not in front of my computer that has BS loaded on it. But, I think that you would not be hitting this mash efficiency if you were not draining too much liquid and then boiling off more.
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Old 10-02-2013, 05:46 PM   #10
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I am a bit confused. Are you hitting your OG but missing on preboil? Or are you having to boil for a very long time to hit your OG because your preboil is low? Unfortunately, I am not in front of my computer that has BS loaded on it. But, I think that you would not be hitting this mash efficiency if you were not draining too much liquid and then boiling off more.
I'm confused too! I just gave you the numbers that BS shows me after all the data I put in. No, I missed my gravity at both, pre-boil (but made up for most of it by an additional 0.7 gal) and before putting it in the fermenter. My volume measurements are probably not accurate at that point so maybe I still hit my 68%; all that would take is 0.4 gal more wort.
I guess this thread is supposed to help me boost my overall efficiency by finding out what steps can be improved. I apologize for the confusion and back-and-forth.
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