mash efficiency problem.

[irishplague]

I've been brewing all grain for a few years now and I have about 15 brews under my belt. Every one of those beers has come up short in the OG dept. I use a rectangular cooler with the stainless water line braid, and I batch sparge. I crush my own grain the day of, and usually hit my mash temp pretty close. I got a refractometer so I could check it during the boil and it will read 1.060 during boiling, but when it's cooled down it will read 1.050. What am I doing wrong? I've tried troubleshooting this on my own but I think I'm ready to get some advice.
HELP!

 

[Croyzen]

I'm working through this now. My issue is most likely water, specifically high alkalinity and problem with mash pH, particularly on lighter ales, pales and blonds, etc.

Is your refractometer temperature correcting? Your gravity should be going up as you boil off, not down. It takes virtually seconds for a sample on a refractometer to cool for a reading. Also, it would be wise to zone in on your mash pH. This is the weak link in my process currently. My efficiency is suffering and it's not the process, crush, etc which I'm fairly confident are ok. It's been said the best thing to do is send off a sample of your water to Ward labs for a complete report. I have not done this. You could then build your water using bru n water spreadsheet based on the numbers. You could also build up distilled/DI/RO water. These things have been suggested to me and I'm working through them currently.

What style of beers do you make?

 

[BackAlley]

Where are you taking your sample when you cool down?


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[tooldudetool]

90% of the time low efficiency is due to the crush. Try tightening up your mill a bit and crushing a bit finer. Good luck!

 

[irishplague]

Croyzen, I make stouts, IPA, blonde, and pales, mostly.
BackAlley, I usually take the sample off of my stirring spoon when it's boiling, and when it's cooling I take it off of my thermometer probe.
I'll have to try tightening my mill, I haven't touched the adjustment since I first set it 2 years ago.

 

[helibrewer]

I've been brewing all grain for a few years now and I have about 15 brews under my belt. Every one of those beers has come up short in the OG dept. I use a rectangular cooler with the stainless water line braid, and I batch sparge. I crush my own grain the day of, and usually hit my mash temp pretty close. I got a refractometer so I could check it during the boil and it will read 1.060 during boiling, but when it's cooled down it will read 1.050. What am I doing wrong? I've tried troubleshooting this on my own but I think I'm ready to get some advice.
HELP!

You want to analyze this at two stages; 1) mash (conversion efficiency), and 2) sparge (lautering efficiency).

When your mashing is complete, take a reading and compare it to this chart. Enter the chart at your grist ratio:

So if your ratio is 1.53 and your SG is 1.078, your efficiency would be 97.5% (78/80). You should be in the 90+% range. If you aren't then you have issues with pH, crush, or temps.

Now after sparging use this table to figure out how much sugar you left behind:

Use any of the 4 ratios you want, you can mix cold tap water, it doesn't matter for this test. So if you mixed 1qt/pound and your SG was 1.010, you left 12 percent behind. Subtract the resulting value from your conversion efficiency and you will have your overall mash efficiency as a percent (97.5-12=85.5). If you are leaving a lot of sugar behind (less than 90+%) your issues are with your sparging process.

 

[irishplague]

Thanks helibrewer, I'll put those charts to use next time I brew.

 

[PHDrunk]

Helibrewer beat me to it --- separate your constituent lautering and conversion efficiencies using the Braukaiser method. That will help you hone in on the problem. Conversion should be > 90%, otherwise you mostly likely have an insufficient crush (or possibly the pH of the mash is out of whack).

Also, do you have a hydrometer on hand? Your refractometer measurements seem suspicious to me. Your pre-boil/boiling wort should have a low SG due to the increased volume (relative to the final product), and heating it should lower the SG even further. By boiling to a lower volume and then cooling to room temperature, your SG should rise significantly. Dropping ten points from pre to post boil should, to the best of my knowledge, be impossible unless you're topping off with water in the fermenter.

Also, regarding the crush, I like Denny's line: "crush 'til you're scared."


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[irishplague]

PHDrunk, I think I might not be letting the wort cool down on the refractometer enough before I test it during the boil, I know it only takes seconds but maybe I'm not giving it enough seconds. And on the crush note, I will definitely try a finer crush, my braided stainless should be able to filter out pretty small particles.