Low OG

[Ghostbuster]

I’ve just switched to all grain after about five successful extract brews and I love it. However, I think my mash efficiency is way off and I need help. I just brewed an all grain American IPA that was supposed to have an OG of 1.067 but ended up with an OG of 1.045. I had 12.25 lbs of grain, 4 gallons of strike water, 5 gallons of 170 degree Sparge water, and the total time of fly sparging and filling up the kettle with 6.5 gallons of wort was about 25 minutes. So......what am I doing wrong? Haha

 

[VikeMan]

What was your grain bill and your actual final volume (after boiling and cooling) including hops/trub? (And was that 1.045 pre-boil or post-boil?)

 

[Ghostbuster]

I had about 7 gallons of wort before boiling And about 5.5 gallons of wort after boiling and cooling. And 5oz of hops in boil.

 

[VikeMan]

Grain bill? (Different grains have different potential extract.)

 

[VikeMan]

Also, what was the temperature of the wort when you measured the 1.045 OG? And was it post-boil or pre-boil?

 

[Ghostbuster]

9lbs pale ale, 3lbs Vienna malt, .25lbs caramel malt 80L.

 

[Ghostbuster]

And the 1.045 was right before I tossed it in the fermenter, so about 65 degrees.

 

[Ghostbuster]

I found the recipe online so maybe there was something wrong with the recipe, but being off by more Than 20 points makes me think it was user error haha

 

[VikeMan]

Okay, so your mash efficiency was about 55%, which is pretty low. You would have needed about 81% to hit 1.067 (given your volumes).

Does your mash tun have a dead space, i.e. was there wort left behind in the tun beyond what was absorbed by the grains?

You fly-sparged... did you note any "channeling" of the runoff through the grain bed?

What was your mash temperature and how accurate is your thermometer?

How thoroughly were your grains crushed?

 

[Ghostbuster]

There was a little wort left over in the mash tun but I’m wondering if maybe I used too much Sparge water that led to that? Not sure about the channeling....none that I noticed anyways. And my goal was 153 for mash temp but It wavered between 146-152 for most of the mash. I don’t have individual heat for my mash tun so I just had to add small bits of boiling water periodically to maintain temp. And grains seemed to be crushed pretty good. A good mix between finely crushed and partially crushed with no whole grains that I could see. Thanks for taking the time to help me with this btw. I really appreciate it.

 

[Ghostbuster]

I should add, I also did an iodine test at the end of the mash to see if starch conversion was completed and it passed.....

 

[VikeMan]

Given everything, my guess would be some un-noticed channeling. How were you delivering the fly sparge water to the tun? Particularly, was there some way of gently adding the water in and keeping it from going to one spot?

 

[Ghostbuster]

I have one of those sprinkler heads coming off my HLT. Not sure what the technical term is for it but it’s part of the Northern Brewer all grain kit. It seems to do a relatively good job of dispersing the water and not disturbing the grain bed.

 

[Ghostbuster]

This is what I use

 

[VikeMan]

Well, I'm pretty stumped, so (maybe) last questions....

You say the crush looked pretty good. Did you crush the malt yourself, or was it done by an LHBS? (Given this was your first all grain batch, it may be that the crush wasn't great, but you could use more experience judging that.)

Do you know what the mash pH was?

Does your hydrometer measure 1.000 with plain water at whatever temperature (60F or 68F) it's designed for?

ETA: Is it possible you had more volume than the "about" 5.5 gallons you mentioned?

 

[Ghostbuster]

I crushed it at the LHBS but I crushed it myself and haven’t heard of anyone else having an issue with the grain mill. But that could be part of the reason maybe. I didn’t measure ph....that’s my next step in improving my process. And I just bought the hydrometer because my other one broke so I haven’t checked it with water yet but that’s probably a good idea to test that. Although, I double checked with my refractometer and got the same reading when the wort had cooled

 

[VikeMan]

Assuming the hydrometer is good, then beyond measuring the pH and getting the crush a little finer, the only other thing that comes to mind would be to try a batch sparge next time instead of fly. Batch sparging normally yields a lower mash efficiency than fly sparging, but if your efficiency actually increases, it could point to a fly sparge issue (hidden channeling).

Come to think of it... 25 minutes is a pretty fast fly sparge. That could also be a piece of the puzzle.

 

[Ghostbuster]

Ok yea that’s a good idea. And yea I was kinda thinking that was fast. I think I need to adjust my valves or something because it seems like they are either pouring out or dripping, no in between.

 

[TurnipGreen]

You said this is your first all grain batch? I’m going to throw something super simple out there. Did you stir up the mash enough?

I think you should brew another batch quickly and see if it’s just a matter or working the kinks out of a new system and process. It took me three or four batches to get a somewhat consistent efficiency. And I’m sure I don’t calculate it correctly, but it’s consistent.

 

[bracconiere]

uhhh, 25 minutes for a sparge doesn't seem long enough.....i spend over an hour sparging....i remember when i ran it full bore, i got crap effec too, learned to slow it down, went from 60's to 80's.....

 

[Ghostbuster]

Well not my first, it’s my fourth all grain brew. I’m just new to it and learning everything from scratch. But this is my first IPA. Most other beers I’ve brewed I’ve been in the 1.05-1.03 range for OG (on purpose)

 

[Ghostbuster]

Gotcha. Ok I think I’ll definitely try a longer Sparge next time the . Maybe switch up my Sparge arm some. It doesn’t work very well at low water velocity