Author Topic: Efficiency drop after switching from bazooka screen to false bottom  (Read 2535 times)

Offline tmm786

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Hey everyone,

Been a member for several years but it's my first time through the forums.  I have a new problem that I am having a hard to figuring out the answer to.

I switched to all grain a couple years ago and started out with a 10 Gal Rubbermaid cooler for a mash tun with a Bazooka screen.  I changed my process slightly as I learned more, but ultimately ended up right around 70% efficiency by mashing in at ~150 degrees F, mashing out at ~168, batch sparging at ~168 and draining to my kettle.  Over time, my bazooka screen started to "break down" and I decided to replace it with a false bottom.

Now, my problem begins -- I am averaging around 60% efficiency since the swap.  I use the same process.  I have used different grain sources and even purchased and have used my own grain bill on the last two batches.  The 2nd most recent batch I ended up with 5 gallons of wort (as planned) and had a gravity of around 1.040 (expected ~1.050).  This weekend I hit my gravity number (1.050) so I was prepared for better results, but ended up short on the wort and still ended with an efficiency of 62%.

I am close to ordering another bazooka screen and seeing if it corrects my results, but with either method I think my efficiency could be better overall.  So, I am wondering if I am missing something fundamental since I would not have expected an efficiency drop with this type of equipment change. 

Any help would be appreciated, and I can provide more details along the way if needed.

Thanks!
Tim

Offline dmtaylor

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Re: Efficiency drop after switching from bazooka screen to false bottom
« Reply #1 on: August 16, 2016, 02:13:44 AM »
I really don't think it's the mash tun's fault, not much anyway.  You most likely need to mill your grains finer.
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Offline tmm786

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Re: Efficiency drop after switching from bazooka screen to false bottom
« Reply #2 on: August 16, 2016, 02:24:58 AM »
I really don't think it's the mash tun's fault, not much anyway.  You most likely need to mill your grains finer.

I did try that on my most recent batch, thinking I could now go with a finer crush than before.  Although it was a Wit so half of the batch wasn't milled.  Maybe not the best recipe to judge those results?

Offline dmtaylor

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Re: Efficiency drop after switching from bazooka screen to false bottom
« Reply #3 on: August 16, 2016, 02:33:16 AM »
Did you use a bunch of oats or something?  It could possibly hurt efficiency if you had a stuck runoff and couldn't collect all the sweet wort, although in cases like that you can try raking the surface of the mash or add rice hulls to help runoff.
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Offline tmm786

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Re: Efficiency drop after switching from bazooka screen to false bottom
« Reply #4 on: August 16, 2016, 03:47:30 AM »
I used flaked wheat and oats to make up 50% of the mash. Should have used rice hulls (I knew better) but I didn't. Had an almost stuck sparge but got through it. Would have thought low efficiency was entirely do to the grain bill but this issue has happened over the last 4 brew days. Other days were 100% barley but had variables in the grain crush and source.


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Offline Bob357

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Re: Efficiency drop after switching from bazooka screen to false bottom
« Reply #5 on: August 16, 2016, 05:08:24 AM »
Have you checked the dead space in your MLT?
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Offline dmtaylor

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Re: Efficiency drop after switching from bazooka screen to false bottom
« Reply #6 on: August 16, 2016, 11:59:11 AM »
If you see this on every batch, it might be a combination of crush inconsistency, and a dead space issue.  You're batch sparging?  After both the first and the second runnings, you need to tilt your cooler to get every last drop possible out of it.  If you don't, you're leaving a lot of sugar in the mash tun.
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Offline reverseapachemaster

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Re: Efficiency drop after switching from bazooka screen to false bottom
« Reply #7 on: August 16, 2016, 02:55:30 PM »
Definitely would not rely on a recipe with a lot of adjuncts to determine whether you have a system issue in your brewhouse.

If there is a system issue then the first thing I would look at is dead space considering the change in how you are draining out the runnings.
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Offline HoosierBrew

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Re: Efficiency drop after switching from bazooka screen to false bottom
« Reply #8 on: August 16, 2016, 03:03:43 PM »
+2 on the dead space likely increasing noticeably with the change to the false bottom. Extra lost sugars under the false bottom would account for the problem IMO.


Edit - As said, you obviously decrease the sugars lost if you can drain as many of them as possible (ie., tipping the cooler, etc.)
« Last Edit: August 16, 2016, 03:26:26 PM by HoosierBrew »
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Offline denny

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Re: Efficiency drop after switching from bazooka screen to false bottom
« Reply #9 on: August 16, 2016, 03:20:14 PM »
+3 on dead space
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Offline tmm786

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Re: Efficiency drop after switching from bazooka screen to false bottom
« Reply #10 on: August 17, 2016, 02:43:41 PM »
Thanks for the feedback everyone.  Seems like a theme with deadspace.  I have a couple recipes in mind in the next few weeks that are 100% barley and maybe the feedback here will help me dial it in.


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Offline Visor

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Re: Efficiency drop after switching from bazooka screen to false bottom
« Reply #11 on: August 18, 2016, 03:04:44 PM »
Assuming you're using a false bottom which was designed for round coolers and has a central sump pickup, I wouldn't think you'd have more than a cup or two of liquid left, unless the hose connecting the sump to the valve becomes disconnected. I use a 10 gallon round cooler with a false bottom and BIAB, the only time I had more than a pint left in the dead space the hose had come loose so the siphon effect was broken. Titling the cooler will only leave you with more dead space loss if your false bottom has a central sump pickup.
  Measured what was left in the dead space today, a little over half a cup. Not enough to make any difference in OG. If the siphon is disrupted due to too fast a runoff near the end [which did happen today] it'll leave a bit under a pint.
« Last Edit: August 19, 2016, 10:59:16 PM by Visor »
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Offline tmm786

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Re: Efficiency drop after switching from bazooka screen to false bottom
« Reply #12 on: August 18, 2016, 10:04:46 PM »
Assuming you're using a false bottom which was designed for round coolers and has a central sump pickup, I wouldn't think you'd have more than a cup or two of liquid left, unless the hose connecting the sump to the valve becomes disconnected. I use a 10 gallon round cooler with a false bottom and BIAB, the only time I had more than a pint left in the dead space the hose had come loose so the siphon effect was broken. Titling the cooler will only leave you with more dead space loss if your false bottom has a central sump pickup.

That is what I am using. I tried to approximate the dead space before and had less than half a gallon. (I haven't measured with just water). Given this, if dead space isn't a concern, then what else could be the problem?  Dialing in grain crush better?


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Offline Stevie

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Re: Efficiency drop after switching from bazooka screen to false bottom
« Reply #13 on: August 18, 2016, 10:36:28 PM »
In theory, the method of filtering wouldn't make a difference beyond the amount of wort lost to deadspace. Any loses in efficiency should be coming from something else.

Offline tmm786

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Re: Efficiency drop after switching from bazooka screen to false bottom
« Reply #14 on: August 19, 2016, 05:44:54 PM »
In theory, the method of filtering wouldn't make a difference beyond the amount of wort lost to deadspace. Any loses in efficiency should be coming from something else.

Which makes it that much harder to figure out. Nothing has changed in my process other than switching from a bazooka to a false bottom.


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