Low efficiency with corona mill :/

[Mojzis]

Bought a Corona mill a few weeks ago. Made a batch of wildflower wheat, efficiency was low (65%). Made a batch today, efficiency was 55%.

Using the roller at my LHBS i was getting around 70-75%. I'm not doing anything different. I wish I took a picture of my crush. It looks like the un-conditioned crush on wiki. It has lots of hulls, not torn apart and shredded.

Here's my process for 5 gal:

Strike water at 162, 15.7 qt to make it 152. Did this for 75 min (temp was right on).

Sparged first with 2 gal at 168-170 for 15 min. Brought my grist temp up to 156.

Sparged second with 3.5 gal at 168-170 for 15. Brought my temp up to 160.

Took reading once the hydrometer with wort cooled to room temp. Got a reading of 1.038. Was looking for 1.042.

Boiled very strong for an hour. Came of with a gravity of 1.040. Estimated was 1.052.

Pretty upset with these results. I'm doing something wrong. I have read the "low gravity" sticky for sparging many times. Still.....has to be my grinding doesn't it?

Frustrating :/

 

[tally350z]

Do you have the recipes for each batch?

 

[Gartywood]

Need the grain bill and volume in the kettle. .004 difference in gravity shouldn't become .012 difference post boil if your volumes were correct. In fact if you started at 6 gallons and boiled down to 5 there would still be about a .004 difference.

(preboil gravity * preboil volume / post boil volume = og)

 

[gabeweisz]

Using washers to make the sides of the places even helped me with mine, as well as cranking it as tight as it would go (I keep it just loose enough for the plate to be able to turn)

 

[Stauffbier]

I have a corona mill too, and I get between 76-80% efficiency with batch sparging. I even got 80% on a BIAB yesterday! Tighten that baby up, and crush it finer. Like they say "crush it till you're scared"! If that gives you lautering problems you can throw a couple handfulls of rice hulls in the mix...

 

[Mojzis]

Do you have the recipes for each batch?

Need the grain bill and volume in the kettle. .004 difference in gravity shouldn't become .012 difference post boil if your volumes were correct. In fact if you started at 6 gallons and boiled down to 5 there would still be about a .004 difference.

(preboil gravity * preboil volume / post boil volume = og)

This batch was 5# 2-row, 5# flaked wheat. Last was 6# 2-row 4# wheat malt.
Pre-boil was around 7.5. Post looks to be 5-5.5. Didn't measure, was in a rush to bottle and finish this batch....

Using washers to make the sides of the places even helped me with mine, as well as cranking it as tight as it would go (I keep it just loose enough for the plate to be able to turn)

The mill came with spacers so I don't need washers (the spacers work perfect).

I have a corona mill too, and I get between 76-80% efficiency with batch sparging. I even got 80% on a BIAB yesterday! Tighten that baby up, and crush it finer. Like they say "crush it till you're scared"! If that gives you lautering problems you can throw a couple handfulls of rice hulls in the mix...

I thought you weren't supposed to tighten the mill that much? Shredded hulls means tannins and bitter beer no? I was trying to keep the hulls in-tact....I could tighten it a lot more if I had to.

 

[cincydave]

I have a corona and grind it really fine (BIAB though). I think the whole crushed hulls = tannis thing has been pretty much debunked on some other threads. I would tighten it down.

 

[kh54s10]

Tighten that sucker up and when you think it is too tight, tighten it some more.

Really, I get what I would describe as just short of flour. I think that what you need is as fine as you can get without getting a stuck sparge.

The Corona mill will not quite do the same thing as a roller mill, so shredding of the hulls is unavoidable.

I haven't tried it, but maybe conditioning the grains might help. (I think that is the right term.)
A spray bottle and mist the grain until slightly moist, then mill.

 

[brian2can]

I use a corona and do well efficiency 75 to 80. I adjust so it moves freely and a little bit more. The tannins and bitter would really come through in the mash temp being to high over 170. That is just my opinion.

 

[sonex]

just be aware that too small of a gap could cause stuck sparges. I would make certain the problem is not something else in your process. Did you check the accuracy of your thermometer? if the thermometer is not accurate you may not be mashing at a temp that gives you complete conversion. are you getting the right volume into the fermenter? If you have more volume than the recipe called for that will give you a lower hydrometer reading than expected.

 

[Stauffbier]

Tighten that sucker up and when you think it is too tight, tighten it some more.

Really, I get what I would describe as just short of flour. I think that what you need is as fine as you can get without getting a stuck sparge.

The Corona mill will not quite do the same thing as a roller mill, so shredding of the hulls is unavoidable.

I haven't tried it, but maybe conditioning the grains might help. (I think that is the right term.)
A spray bottle and mist the grain until slightly moist, then mill.

^this^ +1000!

The tannins and bitter would really come through in the mash temp being to high over 170.

This is half true. Tannins will be extracted under certain pH conditions at temps higher than 170F. If the pH isn't in the favor of the tannins then you might not extract any even at higher temps. It's not worth the risk of finding out, which is why we don't sparge over 170F. This is why a lot of people pay such close attention to pH levels during the later part of sparging...

 

[Mojzis]

just be aware that too small of a gap could cause stuck sparges. I would make certain the problem is not something else in your process. Did you check the accuracy of your thermometer? if the thermometer is not accurate you may not be mashing at a temp that gives you complete conversion. are you getting the right volume into the fermenter? If you have more volume than the recipe called for that will give you a lower hydrometer reading than expected.

My thermometers are good, I have checked them both. Honestly I could be putting more in the fermenter than expected. Last batch was supposed to be 5 gal and I ended up with around 5.5-5.75. This time I only added my yeast to 1/3 of the batch. The rest is in a sanitized bucket, i'll put that in with the rest later today. I read a wiki article on how that's supposed to help pitching rate and lower yeast stress. Figured i'd try it. When I add it today ill have an idea how much wort I really made.


I guess the thing to do is measure my boil off and plug that data into beersmith. I have just been going with what volumes it tells me to do.

Then i'll tighten the mill up so i'm grinding the hell out of it. I'll just have to stock up on rice hulls.

 

[sonex]

My thermometers are good, I have checked them both. Honestly I could be putting more in the fermenter than expected. Last batch was supposed to be 5 gal and I ended up with around 5.5-5.75. This time I only added my yeast to 1/3 of the batch. The rest is in a sanitized bucket, i'll put that in with the rest later today. I read a wiki article on how that's supposed to help pitching rate and lower yeast stress. Figured i'd try it. When I add it today ill have an idea how much wort I really made.


I guess the thing to do is measure my boil off and plug that data into beersmith. I have just been going with what volumes it tells me to do.

Then i'll tighten the mill up so i'm grinding the hell out of it. I'll just have to stock up on rice hulls.

no wonder you have such inconsistency, if your recipe is for 5 gals and you over shot by 3/4 of a gallon your hydro readings will always be lower than anticipated. need to get your volume and boil off calculations honed in on.

 

[Mojzis]

Yup, seems like this batch is .5-.75 gal high again. Glad to know that's where i'm messing up, i'll look into figuring out my boil off for next time. Every batch I make is another lesson learned .

You think that can throw off my readings by that much?

 

[sonex]

Yup, seems like this batch is .5-.75 gal high again. Glad to know that's where i'm messing up, i'll look into figuring out my boil off for next time. Every batch I make is another lesson learned .

You think that can throw off my readings by that much?

3/4 of a gallon is about 15% too much volume so I imagine it will throw off your readings by that much.