Efficiency - what changed???

[brownni5]

My efficiency has dropped a lot over the past year, and I can't figure out why. Let's start by saying that I understand that one can make good beer with any efficiency and I've very much liked most of what I've brewed with the lower efficiency. Still it confuses me. Here we go:

For my first 10 or so AG batches, I was getting 70% mash efficiency, really on the nose, every time. I would buy crushed grains, batch by batch. I was happy. Then I bought a mill. Immediately, my efficiency went up to 75-78% for the next 2 batches - "ok, that's the new normal" I thought. Wrong. Since then (8 batches?), I've been getting about 65% eff., or thereabouts. What changed after those first 2 "good" batches? I bought bulk grain instead of having my grain bills packaged together. Nothing else, at least not that I can think of, has changed. Same mash tun, same batch sparge, same treatment for RO water, calibrated scale and thermometers, same method for measuring wort in my same kettle.

I've tried longer mashes, cooler mashes, hotter mashes, different base grains, different braided hose in my 48-quart cooler mlt, double milling, triple milling, probably other stuff I can't think of now. All right around 65% eff. I have not tried pre-milled pre-packaged grains again. What am I missing? I'm beginning to lose sleep over this! Again, I've been happy with my brews for the most part, and I understand about "relaxing," but as a scientist, I HAVE to figure this out. My old 70% eff. is my White Whale.

Has my old trusty cooler MLT "worn out?" Help!!!

 

[Rockn_M]

A few things to think of and test.
1. Is it possible the gap in the grain mill increased? Or the rollers aren't as rough to grind?
2. Do you measure pH?

 

[SEndorf]

There's so many variables. I'll throw in a couple ...
-dbbl check your mill gap
-double / triple milling sometimes improves efficiency. Other times it creates channeling and has the opposite effect.
-Make sure your runnings into the boil kettle are trickling - Not too fast.

 

[kh54s10]

I would check the gap on the mill first. Then check the calibration on all your measuring devices.

I don't get as consistent efficiency numbers as that, even with milling my own grain. It averages 70 but will go from 66 to 74.

All those changes should have caused a variation in your efficiency. Guess I can't really help....

 

[doug293cz]

You didn't start brewing bigger (higher gravity) beers by any chance, did you?

Brew on

 

[Gnomebrewer]

You could guess at many different factors and might still not know what's wrong. The best way to work out the issue is to take measurements throughout the entire brewing process.

Start by accurately measuring strike-water and grains so that you can measure mash-conversion efficiency - this is the amount of sugar in solution in the mash before the sparge. It should be higher than 90%, more likely 95% or higher and possibly 100% (due to inaccuracies it might even measure a bit higher than 100%). If it's lower, then the crush is your issue (or maybe pH). I get 95%+ efficiency with my mill set to about 0.030" and a 60 to 75 minute mash. Use this spreadsheet
http://braukaiser.com/documents/efficiency_calculator.xls

Next, measure your mash lauter efficiency - this is how much of the potential sugar makes it to your boil kettle from the mash tun. If you see a big drop here then your issue is in the sparge - you might have channelling or be leaving behind too much wort. A quick and easy double batch sparge should give about 85% efficiency at this point. A well performed fly sparge may be a bit higher. BIAB with a solid squeeze could be higher still. It is gravity dependent though - higher gravity beers generally have poorer efficiencies.

After that, measure your final efficiency. If all was good up to this point but your brewhouse efficiency (into the fermenter) is low, you must be losing some wort after the boil. Are you leaving a lot in hoses? Leaky hose?

 

[brownni5]

Thanks for the replies, but all sound like dead ends - simple system, so no hoses other than the same one leading from my same old mash tun, I've checked the.mill gap, I check pH with a calibrated meter, I almost always brew mid-gravity beers, I did notice some channeling on my last brew, but never saw that before, so that didn't seem to hurt. I suppose I'll keep working at figuring it out.

Typically I see the problem leading into the boil kettle, so I'll concentrate more on my sparge.

 

[Big Monk]

Thanks for the replies, but all sound like dead ends - simple system, so no hoses other than the same one leading from my same old mash tun, I've checked the.mill gap, I check pH with a calibrated meter, I almost always brew mid-gravity beers, I did notice some channeling on my last brew, but never saw that before, so that didn't seem to hurt. I suppose I'll keep working at figuring it out.

Typically I see the problem leading into the boil kettle, so I'll concentrate more on my sparge.

Poor conversion? If your lautering setup hasn’t changed, I’d be looking for conversion issues.

 

[Gnomebrewer]

I did notice some channeling on my last brew

Batch sparge, or fly sparge? Channelling doesn't really hurt a batch sparge, but does hurt a fly sparge. If you've been fly sparging, give a double batch sparge a try - it's easy and fast and will fix efficiency due to channelling.

 

[doug293cz]

Also, if your conversion eff is good (see 4 posts above), and you are fly sparging, give batch sparge a try. If efficiency goes up, then your fly sparge process is the issue.

Edit: @Gnomebrewer sneaked in while I was typing.

Brew on

 

[Soulshine2]

I second the (double) batch sparge . I batch sparge twice myself. I tried a fly sparge on my first AG batch and adopted the batch sparge soon after. It just made more sense to do. Run your strike water about half of your intended boil volume (so , if your pre-boil volume is 7 gallons ,mash with 3.5 ,first sparge run 1.75 gallons and same for the second . )and the next consecutive batch sparges , run half of the remaining amount and then again just so your boil volume comes out right. It works for me. No complaints, no issues like you're having.
I run the same temperature of sparge water as the mash . I wait at least 10 minutes and I stir the sparges ,so I do end up doing another vorlauf ,only because I don't want cold spots,dead spots or to leave any fermentable sugars in the tun. Why would I ,right?
I get consistent numbers, i.e. target gravities.
Check your hydrometer for cracks. I had a tiny crack and didnt notice until I saw water in the bottom of my hydrometer. I've no idea how long it'd been there.

 

[Shade]

Gnomebrewer’s advice is good - check the gravity of your first runnings and preboil as well, there are calculators around for what these should be. Then you can tell if it’s the mash or lauter stage, or both.