Fly Sparging question, my OG has been low the past 2 brews

[DancingBull]

Hello,

I've been all grain brewing since February and the last two batches I have been .0010 off (low) on my OG. (1.050 vs. 1.060 for example)

Note: Two things different from my previous brews, I am increasing the final volume from 10 gallons to 13 gallons (I increased the grain bill size) and I have begun folding the mash during sparging, more on that later.

Here is the latest recipe: (13 gallons final volume, 14 gallon pre-boil) Porter, supposed to have an OG between 1.062 and 1.059

Grain (crushed at the brew store for me)
16 lbs Rahr 2 Row
4.5 lbs Weyerman Rye Malt
4.5 lbs German Dark Munich Malt
2.5 lbs English Medium Crystal
1.5 lb English Black Malt
(29 pounds total)

Hops
1 oz Nugget hops 60 min.
2 oz US Fuggle 30 min
3 oz Cascade 5 min

We mash at 153 degrees F for an hour, using 7.5 gallons of water (1 quart per pound of grain), mashout at 170 degrees F (about a gallon of water) for 10 minutes and then circulate the wort with 2 small sauce pans for about 15 minutes. Finally the iodine test shows we have fully converted.

While the mash was resting, I heated 14 gallons (2 quarts per pound of grain) to 180 degrees F and after mashout transfer this between 2 10 gallon Igloo coolers,, lids on them after transferring. (I heat to 180 as i anticipate heat loss during the transfer to my igloo coolers.)

Next I fly sparge using the Northern Brewer Siphon Sprayer and sparging takes me about an hour to get my volume of 14 gallons pre-boil. While i am sparging, I am keeping the sprayer about 2-3 inches above the grain bed, and my brew partner gently folds the grain. I notice as the wort is coming out of the mash tun into my brew kettle, the color changes from darker, to lighter, and back to darker.

Something else to note is once we hit our 14 gallons of pre-boil, we continue to sparge and still come up with another 2 gallons of wort collected in another bucket, it's pretty consistent colorwise with the 14 gallons. I haven't taken a gravity reading on the pre-boil wort, FYI.

Finally we boil for an hour, add hops accordingly, and we still ended up with an OG of 1.050.

Any advice or thoughts on what might be the issue?

Thanks for reading.

 

[Eighty2Fifty1]

If you have the space in your boil kettle, you could boil the additional wort down to concentrate it. The only downside is the possibility of tannin extraction. Most people say to stop sparging when your running hit 1.010. I fly sparge as well, and I typically use a grist ratio of 1.25 or 1.5 qt/lb, which is thinner than yours. Mash tun space restrictions may dictate this for you though. I use a keggle for a MLT, so I have plenty of space. The thing I really do differently is that I don't touch my grain bed once I've mashed in, and I try to keep about an inch of water above the top of the grain.

 

[RM-MN]

Grain (crushed at the brew store for me)

There's the prime suspect. The mill got readjusted or is worn and the grain isn't milled quite the same.

 

[RussPDX]

I agree that crush is the first place to look. Also, what efficiency are you planning your recipes at? I would check that you are scaling properly.

I always take a reading on the running so right before I shut off the sparge (I fly sparge). My target pre boil is 12.5 gallons for 11 into the fermentor. I used to find that I would be stopping at around 1.025 or so and unless I kept collecting more and boiled down I was around 62% mash efficiency. After asking here and others I really started paying attention to the crush. I double crush the grains and my effeciency is more like 80% now and when I get to my 12.5 gal, I am closer to 1.014. Some variation is expected due to different grains, lots, and malt houses on occasions, but by monitoring the runnings at various points I was able to see that I was leaving sugars behind, and then exactly what improvements I was getting.

Not sure if that helps you find your one point, but the more you measure the easier it is to compare batches and find issues and solutions later. I have a refractometer for fast gravity readings and I love it.


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[OleGoatBrewing]

X3 on the grain crush. Once I bought my own mill the - numbers stabilized for me.

 

[wheels4]

It could most certainly be the crush and check that first. I had a similar problem when I went from 5 gallon batches to 10 gallon batches. Also when I was doing bigger brews (anything over 1.06) my efficiency would drop. I had my 5 gallon system dialed in to give me 72-75% but on bigger beers it would be around 65%. When I started doing 10 gallon batches my efficiency suffered and I could only get around 68% at best. One day I made a really big beer and did not have the room in my mast tun to do a mashout. Well my efficiency jumped to over 70% and this was on a bigger beer. I have no idea why but without a mashout my efficiency is where it was on my 5 gallon system. If I want to do a mashout I will make a thicker mash and my efficiency does not seem to suffer as much. Try doing a batch with no mashout and make sure to keep at least an inch of hot water on top of the grain at all times. I no longer do a mashout and consistently get 72% efficiency.

 

[RussPDX]

Wheels - the difference could be in rate of extraction. When you mash out are you doing an infusion step? Or direct fire? If you are adding water and depending of how you are draining you tun you could have either a pocket of higher gravity wort trapped in dead space, or you may be diluting a bit and need to run more off to get all the good stuff.

Have you noticed a difference in your the gravity of the final runnings between the mash out and non mash out methods? I wonder if you are stopping higher on the mashout and if you ran more off and boiled down more if you couldn't get the same or better efficiency. Of course this is a time issue. I had that same issue and have mitigated it through better milling.


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[wheels4]

That is what I think is happening. In essence I'm making the mash to thin and need to collect more of it and boil it down. It is easier to just not do a mash out which dilutes the wort. When I did a mash out I would just add the amount of 200 degree water to meet the 168 degrees. If I was direct firing (building a stainless 42 gallon tun now) I don't think I would have this issue. I have noticed no difference in final product with or without mash out though.

 

[RussPDX]

Another change that I had made and didn't even think about until reading your reply is that I stop adding sparge water when I still have about 3 gallons to collect to collect on a 12.5 gal total collection. I think it is about that, I actually judge from what is left in the HLT but I should take better notes on it. This way I am not further diluting what is in the MLT as I am running off. Essentially creating a fly sparge until all the needed water is in the MLT and en draining the remaining batch. Since I am pumping out of the MLT I am careful. It to cut it too tight, but I think that has helped also and could solve your issue.

Of course if you are getting the performance without the mashout then it is a time saver, but you might see a jump in efficiency if you try it this way.


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[Jaybird]

a few things. 1 or x4 crush is really a HUGE thing. false bottom stability is another. temps of the sparge water is yet another. I personally don't mash out but probably should. So having a False Bottom that will let you circulate FAST! REALLY FAST to clear your wort without loosing temps is helpful. A lot of people that come into the store that I talk to are not keeping their sparge water hot enough as well. I would target 175* knowing that the temp is going to drop about 5* by the time it gets through your water cap on the grain bed. I would suggest taking a grain bed temp about 2-3" below the water cap and adjust water temps accordingly to hit 170* I think you'll find your temps are about 5* lower than your target there and thus working against you.

Good luck man hope that helps.

Cheers
Jay