Extremely Low OG - Multiple Batches

[JScottTuck]

Hi all. Hoping for a bit of advice. I'm still new to brewing, so I'm still learning the ropes. Since switching arrest from BIAB to full all-grain with sparge, I've been missing my OG by 10 or 11 points, resulting in my last 3 batches missing their final target ABV.

At first, I thought the size of my mash tun. I was using the 72qt Coleman Xtreme, and I was attempting to fly sparge. Ended up picking up a Rubbermaid 10 gallon cooler and used it today.

Once the mash settled, I was at 152. After the hour rest, I was at 149. I started with just into 4.5 gallons of water.

I vorlaufed with a pump until clear, then began my fly sparge. The water coming out of my HLT was at 175. I was using a hose from the HLT to drip down into the mash with this: Eagle Brewing BE510 Siphon Spray Wort Aerator https://www.amazon.com/dp/B00ODSS5J8/ref=cm_sw_r_cp_apa_i_YNuQCbP485YJX

I do feel like I sparged too fast. My HLT ran out of water after about 10 minutes; although, my overall sparge lasted for about 22 minutes in total until I hit my 6.5 gallon target and stopped. There was about a gallon of water left in the mash tun. I couldn't really get a good spray going without letting the flow from the HLT speed up a bit.

OG came out to 1.042, while my target was 1.053 assuming a 70% brewhouse efficiency, which I obviously didn't get.

I'm thinking that my sparge technique is likely the cause, so I'm guessing that I need to switch to batch sparging, unless I want to get a sparge arm. I also get my grains milled at All Seasons homebrew shop. I'm wondering if I need to perhaps ask for a finer grain crush, or if I should just bite the bullet and get by own mill, so I can control that variable.

Any help would be greatly appreciated. I want to stop these missed targets and low ABV beers!

 

[Big Monk]

Sounds like you may be missing your Pre-boil gravity which is a sign of issues in the mash itself.

Have you measured pre-boil gravity and compared it against what you’d expect?

 

[Gnomebrewer]

To isolate where the issue is, accurately measure the volume of mash water and take a gravity reading at the end of the mash. From that you can work out your mash conversion efficiency using this spreadsheet
http://braukaiser.com/documents/efficiency_calculator.xls
Then measure the volume and gravity of your preboil wort to get your mash lauter efficiency. You can use the spreadsheet above or any one of a number of spreadsheets to calculate this efficiency.
Mash conversion efficiency should be close to 100%. If it's not, you need to mash for longer. If you just can't get near 100%, you most likely have a crush issue (commonly grains that aren't crushed at all), or maybe a water issue affecting pH. A rest at about 160F really helps with the final bit of extraction and conversion.
If mash conversion is good, but mash lauter is bad, the issue is your sparge. A simple double batch sparge is generally more reliable (easier) than a fly sparge and should give somewhere around 85% efficiency (depending on various factors including gravity of the beer). If mash lauter efficiency is good but overall efficiency is poor, the the issue is losses to trub/chillers/hops. Overall efficiency can go close to mash lauter efficiency if you dump all of your wort into the fermentor.

My guess would be that you have a combination of poor crush (not mashing for long enough to get full extraction of starch and conversion) and channelling in your sparge.

 

[RPh_Guy]

To second what @Gnomebrewer said ...

I'm thinking that my sparge technique is likely the cause

Sounds like it.

I'm guessing that I need to switch to batch sparging, unless I want to get a sparge arm.

Exactly. Channeling is a problem.
I personally don't think fly sparging is a good method at the homebrew level. Batch sparging or even no-sparge BIAB can hit great efficiency numbers.

I also get my grains milled at All Seasons homebrew shop. I'm wondering if I need to perhaps ask for a finer grain crush, or if I should just bite the bullet and get by own mill, so I can control that variable.

Finer crush may obviously help, but too fine and the sparge gets stuck.
I think a mill is a good investment.

 

[GoeHaarden]

Since switching arrest from BIAB to full all-grain with sparge

What everyone else said...

Were you doing true BIAB (which is all-grain btw) or were you doing extract and steeping? If you were doing extract/steeping then water chemistry/pH may be a cause for poor efficiency in a mash.

 

[CascadesBrewer]

As far as fly sparging...you don't need a fancy system to get decent efficiency. My fly sparge system was based on an insulated bucket with a false bottom. I would scoop water into a colander/strainer that sat on top of the grain bed. I was getting around 75% brewhouse efficiency. It was a bit inconsistent with occasional stuck/slow sparges, and overall it was a time consuming and manual process. Also, my 6.5 gal bucket limited me to around 16 lbs of grain.

I upgraded by getting rid of my lauter tun and switching to BIAB (using my 10 gal kettle). For me, eliminating the entire sparge process reduced my brew day by and hour and eliminated one of the least enjoyable steps. With a dunk sparge, I saw a boost to around 80% efficiency. I have been doing full volume mashes lately with around 75% efficiency.

How big is your boil kettle? Some people do "mash in a bag". It is similar to BIAB but you mash in a separate cooler (which your 10 gal one would work well for). A benefit of BIAB/MIAB is that you can crush your grain very fine to boost efficiency without issues with stuck sparges.