Another Fly Sparge Volume question

[gbarker121]

Howdy,

I seem to be having a hard time hitting either my gravity numbers or pre-boil volumes and I wonder if part of it isn't a fundamental misunderstanding about Fly Sparging technique. Typically, when I hit my volume, my runnings are still way above 2 degrees Plato and my pH is nowhere near 5.8 which is where I usually draw the line. So, I keep going, not wanting to give up those sugars. This weekend for example, I was making an 11 gallon batch, expecting a pre-boil volume of 17.3g and I stopped runnings at 20.5g with a Brix of 5 and a pH of 5.4. To correct my volume I boiled the wort down to 17.3 gallons (about 90 minutes) and then started the "real" 90 minute boil with it's hop schedule. The post boil volume was right but my gravity was off. Expecting 1.080 and got 1.090ish (Obviously, I'm getting the sugars out so I don't *think* I'm sparging/lautering too fast... am I?). Not a big deal really. I added a gallon of top up water and my gravity is fine now; though I have a gallon more wort than I expected.

Clearly I'm missing something.

In BeerSmith 2, in the Mash tab of my recipes, I've noticed the instruction "Fly sparge with X gallons". I've been ignoring it though because in every other discussion on fly sparging I've read, the simple guidance has been: Always keep an inch or so of clear water over the grainbed".

So, my over-simplified question is, "Which one is right?". Should I "Always keep an inch of clear water over the grainbed" until my runnings tell me to stop? Or, do I "Fly sparge with X gallons"; keeping an inch of clear water over the grainbed until I run out of sparge water (while continuing the lauter)? A side question: If the answer is to just keep an inch of water over the grainbed, what is the value of the sparge water calculation in BS?

Or am I barking up the wrong tree entirely?

Thanks for any help,

G

 

[GilaMinumBeer]

Try keeping an inch of water over the grain bed until you have sparged with X gallons of water in order to reach your pre-boil volume and gravity.

 

[Umaine_Moose]

I batch sparge so I dont have any experience with fly sparging but Beersmith2 calculates your preboil gravity based on an estimated mash efficiency. If your mash efficiency is higher than the estimate that could be causing the error in the pre-boil gravity. Beersmith2 will adjust the estimated efficiency based the efficiency of your past mashes, but I will take sometime to accurate.

So you may want to compare the two (I the mash tab), and consider removing some grain to high your gravity numbers, I would think this would help with the volume as well.

 

[wailingguitar]

It's actually a very simple calculation to get you to where you need to go... Start with a volume of 1.2 to 1.3 qt. of strike water / pound of malt... so like 12qts/3gallons for a 10# malt bill. You will have a loss of approximately 10% of your # weight of malt in gallons ... so a 10# mash will lose about a gallon of water... 15# mash a gallon and a half.... SO, in the above you yield 2 gallons of wort to kettle (3 gallons strike - 1 gallon loss), to achieve a 6 gallon volume in the kettle you will need to sparge with 4 gallons... depending on your mash tun you may need to calculate a loss there as well... if you have, say 1 qt standing in the mash tun after a full drain of liquid, add 1qt to your sparge. SO, in the above example; 3gallons strike water - 1 gallon loss to mash - 1 qt loss to dead space = 1.75 gallons wort to kettle... 6 gallon target - 1.75 gallons = 4.25 gallons sparge water needed to hit volume. Do it this way and you will always hit your volume dead on at the end of your run off with out having to worry about over sparging, etc. This is the method I use commercially and at home and it has never failed me. Also, you really needn't worry about keeping 1" or whatever amount of sparge water over your mash as long as there is SOME water of the mash until near the end of run off... heck, if your mash tun will hold it, and has decent insulation, go ahead and get it in as quick as you like and be done with it

 

[chickypad]

The idea behind stopping fly sparging at about 1.010 and/or keeping it below pH of 6 is to avoid extracting tannins. You should stop if you get that low, but you don't have to keep going until you get that low. Stop when you hit your intended boil volume. You'll want to adjust the efficiency and settings in Beersmith to match what you actually get on your system, not the other way around. You should be able to dial it in if you take good measurements over a few batches. I guess if you want to chase efficiency and sparge to the max go ahead, but it seems crazy to me to sparge 3 gal over then have to boil for 3 hrs. Besides, I'd think the cost of the extra propane would outweigh the cost of a few extra lbs of grain.

 

[Yooper]

The idea behind stopping fly sparging at about 1.010 and/or keeping it below pH of 6 is to avoid extracting tannins. You should stop if you get that low, but you don't have to keep going until you get that low. Stop when you hit your intended boil volume. You'll want to adjust the efficiency and settings in Beersmith to match what you actually get on your system, not the other way around. You should be able to dial it in if you take good measurements over a few batches. I guess if you want to chase efficiency and sparge to the max go ahead, but it seems crazy to me to sparge 3 gal over then have to boil for 3 hrs. Besides, I'd think the cost of the extra propane would outweigh the cost of a few extra lbs of grain.

That's what I was going to say.

Sure, you don't want to "give up" sugars, but if your runnings are above 2 degree Plato, that's above 1.008 so it's "safe" from tannin extraction- but if your current preboil gravity is 1.060 at that point, it's diluting what you have! What I mean is this- you don't want to leave sugars behind but by adding more water, and having a gravity of say, 1.012, that's actually diluting the wort that you already obtained and the first runnings may have been 1.080, and as time when on it may have been 1.040, etc.

Sure you can maximize your efficiency by getting every drop of wort out of it over 1.008, but then you'll have to boil 15 gallons of wort (as an example) down to 6 gallons. It'd be far more efficient to start with 7 gallons of a higher OG wort than 10 or 12 gallons of lower OG wort, when you consider the cost of propane or electricity to boil it down.

 

[Yooper]

So, my over-simplified question is, "Which one is right?". Should I "Always keep an inch of clear water over the grainbed" until my runnings tell me to stop? Or, do I "Fly sparge with X gallons"; keeping an inch of clear water over the grainbed until I run out of sparge water (while continuing the lauter)? A side question: If the answer is to just keep an inch of water over the grainbed, what is the value of the sparge water calculation in BS?

Or am I barking up the wrong tree entirely?

Thanks for any help,

G

Oh, so to answer the questions!

Yes, keep an inch of water over the grainbed at all times, or more.

Stop when you reach your boil volume.

The value of the sparge calculation would be as simple as knowing approximately how much water you need. I sparge with 100% RO water- so I want to know how much water I need to prepare! That's really about it. If you always sparge up to your boil volume, then it'll be second nature before you know it.

 

[wailingguitar]

Yes, keep an inch of water over the grainbed at all times, or more.

I think the 'or more' is important here. A lot of people agonize over balancing the flow so that it stays at 1" or 2" or whatever they have heard, no more, no less. It really isn't necessary as long as you don't let the bed go dry, that is the important part. If the mash tun has the capacity and decent insulation, you can get it all in right away and not have to worry about. The only time the top of the bed should go dry is at the end of runoff, if you calculate your water right you'll nail your volume once all the spare water is in.

 

[Bobby_M]

When I fly sparge I don't want to be right on the edge of running the mash dry at the end so I always cushion the sparge with about 2 extra gallons. The top of the grain is dry/damp by the time I'm done collecting, but I do dispose of a couple gallons of wort at the end.

For those casually reading, please note that this is completely opposite of what you want to do in a batch sparge.

 

[gbarker121]

You should stop if you get that low, but you don't have to keep going until you get that low. Stop when you hit your intended boil volume.

Stop when you reach your boil volume.

Lots of good info. Seems I've fixated on "don't sparge beyond 2P or 5.8pH" when I should have fixated on pre-boil volume. Thanks for all of that. I'm not specifically interested in being super efficient (though curiosity about that is sure to come later). I've just been chasing the wrong intermediate numbers. Thanks!

When I fly sparge I don't want to be right on the edge of running the mash dry at the end so I always cushion the sparge with about 2 extra gallons.

I'm pretty well covered there. An electric 30 gallon HERMS/HLT allows for lots of cushion on a 10 gallon batch.

If the mash tun has the capacity and decent insulation, you can get it all in right away and not have to worry about.

I can't make myself dump all of it in at once but I'll keep it in mind and not panic when I check and find 6 inches on top of the bed.

 

[wailingguitar]

I can't make myself dump all of it in at once but I'll keep it in mind and not panic when I check and find 6 inches on top of the bed.

Definitely don't panic... have done it that way in at least a half dozen commercial breweries over the last 25 years

Oh, and to Bobby M, don't worry about the mash going dry (as in not having spare above it) at the end of run off, all that matters is that you have enough water to make your volume... in fact, I have found my efficiency a bit better (couple percentage points) when my total spare volume is as close as possible to nailing the kettle volume without going over. At home I calculate exact, commercially I go about 10 to 15 gallons over because the very last will be a bit cloudy...

 

[Natdavis777]

Like stated, sounds like you just need to adjust your efficiency. If you wanted to though, you could stop collection at your desired pre boil volume for your original batch and collect the rest for a smaller, session beer you you could do on the stove top (assuming you only collect an additional ~2.5gal)

Either way, many would consider this a "good" problem to have