If I'm recirculating my mash through herms coil, do I really count "deadspace" under my falsebottom?

[luckybeagle]

I have a 16g MLT with falsebottom. It sits up kind of high--probably 1.5 gallons' worth of space beneath it. I have a pickup tube on that ballvalve outlet, too, so all but a few ounces makes its way out of the MLT.

I'm a little confused on how to account for this as I'm operating an eHERMS and recirculate my wort throughout the mash (through the HERMS coil in my HLT and back into the mash tun).

I'm brewing a 5.5g batch of a small beer with 9.5# grain bill. At a 1.5 ratio, I'm still only working with a strike volume of 3.6 gallons. The grains wouldn't even be fully submerged if I used that little water.

Should I just increase my strike volume to where the grains are fully sumberged, then just sparge until I hit my preboil volume (and figure out my efficiency based on that for next time)? This logically makes sense as I will probably have much better efficiency with recirculating and fly sparging instead of not recirculating and batch sparging.

This is the FIRST brew on the new system... just trying to figure it out.

Thank you!

 

[kevin58]

Interesting question. I have a similar system but have not run into your conundrum. I would think that you would want the grain bed fully covered with water during the mash even with recirculation.

 

[Keith81]

You need to have all the grains submerged. As far as dead space is concerned, when figuring out how much strike water you need for the mash you have to calculate the full dead space in order to get enough water to submerge the grain. However, if you a trying to calculate the total water needed (mash plus sparge) to reach your pre-boil volume you only use the amount actually left behind, so the diptube reduces the amount lost.

 

[Bobby_M]

Dead space is how much wort would be left if you fully drained the vessel. That's not really what you're asking about. I don't know of an industry term for this but I have always called it Slack Space which I define as any part of the mash that is completely liquid but not in constant contact with the grain bed. That's mash wort that is under a false bottom, in a pump and its plumbing and definitely what's inside a RIMS tube or HERMS coil.

It's easy enough to measure all these volumes and note what it is. From there, assume you want at least 1 to 1.25qt/LB of grain in contact with the grain. The rest can be slack space wort. In that case, set your mash calculator to 1.25 qt/lb and then force in the volume of your slack space to determine Strike volume.

 

[day_trippr]

fwiw, for those who use BeerSmith, the equipment profile refers to the total volume under an FB as "Recoverable Mash Deadspace", as opposed to "Mash Deadspace Losses" which is what gets left behind after lautering. For every quart one increases the former (from the default of zero) BS shifts brew liquor from sparge to mash...

Cheers!

 

[augiedoggy]

simple answer-NO. Better answer ^^

When not recirculating the water under the false bottom really never becomes wort regardless of whether you sparge or not and ends up just diluting the wort in your BK a bit as its transferred over. So the software is also trying to account for this. When you recirculate all the liquid in your MT becomes equally mixed wort (in theory anyway) so this will effect your ratios in a positive way. When fly sparging the liquid left in the "dead space" should mainly be the weak final runnings if anything..

and you want your grainbill fully submerged.

 

[Vale71]

I don't know of an industry term for this...

Overhead?
Although it does mostly sit underneath, so... underhead?

 

[luckybeagle]

Thanks everyone for chiming in. I guess I'm a little confused still.

Here's what I did:

1. Filled up HLT to fully submerge the herms coil (15 gallons approx)
2. Filled up the MLT with 5.3 gallons of water. This is water to grist ratio of 2.2 Quarts/Lb
3. Set PID controlling the HLT heating element to 150F (temp for the recipe - a single infusion trappist single) and began pumping MLT water through the submerged herms coil. **the temperature probe is on the ball valve of the HLT-OUT port**
4. Once I hit 150F in the MLT, I doughed in and ran it for 75 minutes (knowing it would take a little while to raise the temp of the grain bed to my target mash. I'm OK with that and didn't want to mess up the calculation. I recirculated the entire time.
5. I then fly sparged with 3.9 gallons for a preboil gravity of ~87% efficiency over the course of about 75 minutes (couldn't figure out the flow so it went a little long).

The grain bed was the consistency I usually have when mashing in a cooler since there was probably a 1.25/1 ratio above the false bottom. Since the water/sweet wort below the false bottom was recirculating through the grain bed, the volume of strike water was larger, but the grain wasn't floating in a thin soup concoction. Since my efficiency was good, is there any reason I shouldn't continue to do it this way for smaller batches?

Short video of the system and MLT grain consistency: https://www.instagram.com/p/B8-q0x0njee/

 

[Bobby_M]

Nothing wrong with what you did.

 

[luckybeagle]

Nothing wrong with what you did.

Thanks! The water/sweet wort left in the MLT after I hit my preboil volume was significant. I didn't check the gravity of these runnings, but the taste was very watery. Feels a little weird to waste so much water. Then again, the efficiency more than made up for it.

 

[augiedoggy]

I do the same.

 

[luckybeagle]

I don't want to create a new thread for this, and since you guys are fly sparging (and give good advice) I thought I'd ask here.

My wort pH after lautering was about 5.56 IIRC. I did not treat my sparge water (with the exception of campden for chlorine). Since this was my wort pH, do I need to add anything to my sparge water for pH? I know our tap water is just about dead neutral (7.0). I've never filtered or messed with my water profile. We have excellent tasting tap water here in Oregon, but I know certain styles call for different profiles--I'm mostly just curious about the pH corrections (if needed) at this point.

 

[day_trippr]

If by "My wort pH after lautering was about 5.56" you are referring to the last runnings, anything under 5.6 should be fine and should prevent excess uptake of silicates and tannins from the mash.

Otoh, if you are referring to the post-sparge/pre-boil kettle volume pH, something's majorly wrong...

Cheers!

 

[luckybeagle]

If by "My wort pH after lautering was about 5.56" you are referring to the last runnings, anything under 5.6 should be fine and should prevent excess uptake of silicates and tannins from the mash.

Otoh, if you are referring to the post-sparge/pre-boil kettle volume pH, something's majorly wrong...

Cheers!

Hmm, I will do a better job with measuring and recording next time. I believe I stuck my pH probe in the boil kettle during lauter--before it was all done, but not once I had my full preboil volume.

This article says preboil pH should be 5.1 - 5.2, and says that going higher than this can provide a less-than-pleasant hop bitterness. Is 0.3 points significant if that # was an accurate reflection of preboil pH?

https://beerandwinejournal.com/proper-boil-ph/

Is that inaccurate? Water chemistry has been that elephant in the room for me, and with batch sparging there was probably more freedom to ignore it, but I can see how it really shouldn't be ignored if I'm trying to get better.

Thanks for any and all insight!

 

[day_trippr]

Might be a simple answer to those pH readings: taking pH at mash/sparge temperature is very likely going to throw the reading way the heck off - even for most units with ATC, as that high a temperature will typically be well above the ATC range. For example, my Apera pH60 ATC range is 32-122°F. I chill samples to ~25°C before sticking the meter in for that reason.

Anyway, while there are lots of threads on HBT regarding mash, boil kettle, and even fermentor pH, I'd say a compensated 5.56 per-boil pH is on the high edge of desirable. But again, there's a good chance that reading was bogus and the actual pH was significantly lower...

Cheers!

 

[luckybeagle]

Might be a simple answer to those pH readings: taking pH at mash/sparge temperature is very likely going to throw the reading way the heck off - even for most units with ATC, as that high a temperature will typically be well above the ATC range. For example, my Apera pH60 ATC range is 32-122°F. I chill samples to ~25°C before sticking the meter in for that reason.

Anyway, while there are lots of threads on HBT regarding mash, boil kettle, and even fermentor pH, I'd say a compensated 5.56 per-boil pH is on the high edge of desirable. But again, there's a good chance that reading was bogus and the actual pH was significantly lower...

Cheers!

Sounds good ! I was wondering if a temperature correction would be necessary for wort pH like it is for gravity. Now I know... I'll put a small amount through my plate chiller next time for some quick readings on both gravity and pH once lautering is complete.

 

[augiedoggy]

We pour a small amount into a flight glass at the pub and run it under a faucet to cool it before taking samles at the brewpub.