Fly sparging question: mash thickness and mash out water additions

I've got 7 AG batches under my belt at this point and I'm getting my efficency pretty well dialed in (just bought a grain mill to improve consistency, retailer crush has been all over the place). At this point I'm trying to improve my process and I've got the following question about water usage:

Can I drain the ~8" of water to 2-3" above the grain bed (mostly due to the mashout water addition) before sparging without hurting efficiency?
Would less water over the grain bed in the mash tun be a way to improve efficiency somewhat?

Here's some background info, if you want it:

I've been using a mash thickness of ~1.5 qt/lb to prevent stuck sparges, etc. I've also been mashing out, which can require a fair amount of water.
For example, my last batch had an 11.75 lb grain bill. So my mash water was ~18 qts and the mash out water was ~11 qts (in order to get the mash temp up). So all up, my mash tun contained about 7.25 gal of water. For sparge water I heated an additional 6 gal (based on 2qts/lb)

When I go to sparge, the grain bed usually has about 8" of water over it. Over the process of sparging, i keep the water level pretty much constant until closer to the end when I run out of sparge water but still need a bit more to reach my pre-boil volume (usually around 6.75gal). Even then there's still about 5-6" of water left above the grain bed. So I end up draining quite a bit of left over, low-sugar water (<1.020) from the mash tun at the end of the day.

And what's your calculated efficiency from this process?

It's been about 70-75%. 3 of the 7 batches I've done have missed the target OG (efficiencies <60%). I can say confidently that one was due to sparging too fast and the other was due to dough balls (the sparge stuck and when stirring to unset the mash, bubbles and dry-ish grain surfaced). The third was probably due to a poor crush from an online retailer as it had a lot of uncracked grains.
I have been sparging at ~1qt/min which has been fine for hitting OGs < 1.060 (~75% efficiencies) and decent for OG = 1.060-1.065 (~70% efficiency).

I'm going to have another crack at Denny Conn's Rye IPA. Originally I missed the target OG due to dough balls (OG = 1.064 instead of 1.072), but was still fantastic! This time I'm going to slow down the sparge rate to ~0.5 qt/min.

So I think my main issues in the past have been sparging a bit to fast and crush inconsistency, but I want to know if part of my problem has been using too much water.

I should mention that I'm not trying to hit efficiencies over 80%. I just want to get into the 75-80% range more consistently with bigger beers

Personally don't try and hit a certain efficiency, rather to hit the target OG and volume for the batch. I track my efficiency only to reveal issues and for planning purposes. I too average in the mid seventies, but plan my batches for only 70%. This, for just a few dollars a batch, allows me simply stop the sparge when I have what I need rather than trying to wring every last drop of sugars out of it. There are so many variables to efficiency I think it's mistake to think you are going to hit the same number on every batch. It's a good goal to increase what you're getting, but I'm just saying it's not good to cut it so close that even minor fluctuation causes you problems. Especially when it could be avoided with an extra pound or two of base malt...

Demus said:

Personally don't try and hit a certain efficiency, rather to hit the target OG and volume for the batch. I track my efficiency only to reveal issues and for planning purposes. I too average in the mid seventies, but plan my batches for only 70%. This, for just a few dollars a batch, allows me simply stop the sparge when I have what I need rather than trying to wring every last drop of sugars out of it. There are so many variables to efficiency I think it's mistake to think you are going to hit the same number on every batch. It's a good goal to increase what you're getting, but I'm just saying it's not good to cut it so close that even minor fluctuation causes you problems. Especially when it could be avoided with an extra pound or two of base malt...

Click to expand...

Weird, but, I go the exact opposite. If you always hit a certain efficiency, you will always be able to hit an exact OG and not have to adjust on the fly.

I'd rather hit 66% percent each and over time, than 85% today and 70% tomorrow. Then I can know without a doubt exactly how much grain I need and how many hops I'll need to hit a certain SG and IBU.

I've used a ton of different recipes. BYO assumes 65% efficiency, while some of my friends' recipes are 85%. My system gives me 75% each and every time, so I don't have to worry. I just have to adjust the grainbills for my system, and correct my IBUs and I have no issues. It really is the easy way to do it!

nate_e said:

I've been using a mash thickness of ~1.5 qt/lb to prevent stuck sparges, etc. I've also been mashing out, which can require a fair amount of water.
For example, my last batch had an 11.75 lb grain bill. So my mash water was ~18 qts and the mash out water was ~11 qts (in order to get the mash temp up). So all up, my mash tun contained about 7.25 gal of water. For sparge water I heated an additional 6 gal (based on 2qts/lb)

Click to expand...

If you use 1.5qt/lb as a mash-in ratio, and that you add X amount of water for a mash-out, you're in effect raising the ratio to 2.5qt/lb (29qt/11.75lbs). You could easily reduce the mash-in water to 1.2qt/lb, mash-out, and be somewhere around 2.0qt/lb at sparge time.

MC

Yooper said:

Weird, but, I go the exact opposite. If you always hit a certain efficiency, you will always be able to hit an exact OG and not have to adjust on the fly.

Click to expand...

I think the point of the original poster is that he and others don't ALWAYS hit the same efficiency. If you do, good on ya. If you don't, my point is a pound or two of base malt is cheap insurance...

Thanks for the advice. I've just been using Northern Brewer's AG recipes which (I think) are calculated for 75% efficiency and I've been at the low end of that for larger beers like Denny's Rye IPA. I've been using their crush, but I just ordered a Monster Mill 2 so we'll see what the impact of milling my own grain has. I expect an improvement, but I wanted to see if you all thought changing my water usage might be a way to improve or get more consistent efficiency. If not, I'll focus on pH and alkalinity instead.

In general, does mash thickness, or amount of water above the grain bed have any potential (or in your experience, actual) effect on efficiency? It seems like most people think not.

Thanks!