All Grain Deadspace Mash Question

I apologize in advance if this has been answered 10 times, but I couldn't find a clear answer when I searched.

Currently using a Kal clone electric brew setup, 3 x 16 gallon kettles. The MLT has about 2 gallons of deadspace under the false bottom. My current method adds 2 extra gallons to what BeerSmith recommends and subtract that volume from the sparge water. My thinking being that if i leave 2 gallons of water under the false bottom that the grain can't mix with i'll have a thicker mash then intended. My issue has been lower then expected brewhouse and mash effeciency, on the order of 65% brewhouse and 70% mash. I realize I can just add more grain to make up for the loss to hit my target OG, but it seems like maybe there is just a better way to compensate for the false bottom. My concern is the small sparge volume is hurting me. My latest batch called for 25 lbs of grain, 33 qt (8.25 gal) of strike water and 19.25 qt (4.8 gal) of sparge water. So I really mashed with 10.25 gal of water and sparged with 2.8 gal.

If it matters, I do use EZ Water calc to adjust my really soft water and pH and verify my mash pH with an electronic pH meter, so I don't think that's the cause of my lower efficiency.

Any help is appreciated.

-Steve

Well I don't have an answer for you but I will provide my experience with a similar system. I only brew 10g batches right now so I usually have a decent amount of sparge water. I am sure it does effect efficiency when you have a very low amount of sparge water. For me doing a mash out at 168 and leaving it for a few minutes has helped a bunch. I now generally get 90+% conversion efficiency and 80% lauder efficiency. Not great but good enough. I would suggest figuring out your conversion efficiency. Testing the gravity of the sweet wort in the mash tun right before you start sparging will tell you if your getting a good conversion. You can then compare your conversion to lauder efficiency to ensure it is really only a lauder issue and not both a conversion and lauder issue.

I have a 3x 20g Kal clone. I use a jaybird false bottom. I need to increase my mash water by 2.7 gallons to account for the space under by false bottom (2 gallons) and hoses and 50' x 1/2" HERMS coil (.7 gallons). My dip tube in the MLT leaves .5 gallons behind. The site glass "zero" is the level of the false bottom. I still fill the MLT with with the standard amount of mash water according to the site glass while the pump is running which builds in 2.7 additional gallons. I then subtract 1.5 gallons from my sparge water. I only subtract 1.5 because the volume in the hoses and coil (.7g) and under the dip tube (.5g) wont make it to the kettle.

Now on to a test I have been meaning to do to see if it improves lauder efficiency and make life easier. I usually have more water in my HLT then I need for sparging because I have at least enough (12g) of water in my HLT to cover the HERMS coil. Instead of stopping the water pumping from the HLT to the MLT at the sparge volume needed I am going to just let it run though the whole sparge process and simply stop pumping from the MLT to boil kettle when I hit my pre-boil volume. I am not sure if this will help or hurt and I will need to watch to make sure the ph and gravity of the wort does not drop to low. I will be brewing in a few weeks and will let you know what I find.

I do run some sparge water into the MLT before I start draining to the kettle to build up some water on top of the grain bed to help with channeling issues.

That's a lot of text for no answer but hopefully it helps you know your not alone. In the end it's more about consistent efficiency then high efficiency. At our scale I would rather spend a few more dollars on grain and consistently hit my OG. Yet I am still tweaking and messing with my system because its fun and interesting. Good luck.

edit: Here is how my volumes would workout for that grain bill. I am ending up with more sparge water then you are.

Wanted in the kettle = 13
Mash water needed @ 25lb * 1.25qt/lb = 7.8
Grain absorption @ 25lb * 0.125 = 3.125
Wort from initial mash volume = 4.675
Sparge water needed 13-4.675 = 8.325
Mash water + 2.7g for herms and under false bottom = 10.5
Sparge water - 1.5g for herms and under dip tube = 6.825

Total in kettle = mash water (10.5) + sparge water (6.825) - grain absorption (3.125) - herms (.7) - under dip tube (.5) = 13 gallons

Maybe you are going for a lower preboil then me? I boil off just over a gallon in 60 minutes so I end up with almost 12 in the kettle with .5 under the dip tube. and that leaves me with 11-11.5 gallons to split in to two 6g fermenters.

How much liquid is left in your MLT after you drain it? Are you batch or fly sparging?

Also, your pre-boil volume seem kind of odd (assuming 0.125 gal/lb grain absorption).
Seems like too much for a 5 gal batch, and way short for a 10 gal batch. What is your batch size, and what is your target pre-boil volume?

Brew on

Would it be possible to add a dip tube, or drain the mash tun after you're done sparging? That would be the best solution I think.

I appreciate the response, I should have mentioned one rather important fact, this was for an 8 gallon batch. I typically brew 5 gallon batches for the Keezer, but my father has a 2.5 mini keg that I was filling too (with some extra for fermenter trub loss). This was a fairly big OG beer, goal was 1.085, but missed that by a decent margin. As it turns out my refractometer disagrees with 3 different hydrometers (yet another thing i need to figure out)

So I think the problem was i only wanted 9.6 gallons of wort in the Kettle total, boiled down to about 8.6 with .6 gallon of trub loss, for 8 total into the fermenters. The amount needed for the grain and system losses is fixed so the sparge water was quite low, 2.8 gallons for the batch. What I did forget to account for was the loss of the sparge water in the coil and hoses, making notes for the next brew.

I've only had the Kal clone setup for 2-3 months now, was working with a 10 gal igloo cooler with propane burner before so I'm still learning this setup. The old Cooler had just a bazooka screen so I never had to account for a mysterious 2 gallons of dead space that isn't really dead space. BeerSmith doesn't have a way to account for that or the sparge water loss in the hoses and coil, at least not that i've found, but i've only been using that software for 5 months.

So that was a long winded response, sorry. I wonder if I'd be better off recirculating wort in this situation, if it comes up again (High gravity beer). I also think i really need to make an effort to mashout, even if it takes an extra 30 min. I'm really curious if your test works, I also have lots of water left in the HLT, enough to cover the coil. Please let me know how you make out with 'over' sparging.

Edit:
I took so long to reply (dang work) that I missed the other replies.

Right on with the batch size, 8 gallons, should have mentioned that in the first post. The MLT is nearly empty and does have a 'dip tube' of sorts, less than 1/2 gallon of liquid left in there at the end of sparging. I do fly sparge, leaving 1" of liquid on the grain bed, however that doesn't last long as ~3 gallons went fast!

A mash out will only improve your efficiency if your saccharification is incomplete. If saccharification is complete, then the mash out will denature the amylase, and stabilize the sugar profile (molecular weight distribution) and wort fermentability.

Your biggest efficiency detractor is probably the high OG target, combined with limited sparge volume. Mash recirc might help, as you would get more sugar dissolved in the deadspace wort, leaving less that needs to be recovered by sparging. Mash recirc can also help with saccharification rate by overcoming some of the diffusion limitations in a still mash.

Another thing you could have done is to sparge more to recover more sugar from the mash, and extend your boil to get rid of the excess volume.

Brew on

I had hoped a mashout might help 'release' the sugar a bit more into the sweet wort before sparging, but wasn't sure if that was really the case. This brew may have just had a bad combination of issues that made it particularly inefficient. I do continuously recirculate the mash for the whole 45 or 60 min mash, but this was more to keep the temps up and consistent in the bed, I only assumed that would help not hurt conversion.

Sparging more then boiling down more makes great sense now, wish I'd thought of it on brew day!

Is there anything else that people do to account for the 'dead' space under a MLT false bottom? Other than borrow some water from the sparge that is.

Thanks for the help so far