2nd Attempt at Fly Sparging & low efficiency -- Feedback Needed

[Vintage63]

I've been AG brewing for about 1.5 years, but always batch sparged in a 10 gallon cooler with great results.

My rig is now set up for fly sparging with March 809 pump and today was my second brew on the new system.

I only hit about 55% efficiency and an OG of 1.036, when it should have been closer to the 1.060 range.

What is going on? Here I thought I had learned AG brewing pretty well and now I'm not getting close my numbers.

Here is the recipe I brewed today (Oatmeal Stout):

6 gallon batch, 75 minute mash at 154, 60 minute boil

9.4 # Maris Otter
1.0 # Flaked Oats
0.75 # Chocolate Malt
0.75 # Victory
0.50 # Crystal 80
0.50 # Roasted Barley
0.25 # Black Malt (black patent)
1.90 oz Challenger at 60 minutes

Should I have fly sparged longer? I only did for about 20 minutes. Would this have an effect on the efficiency?

I had about one inch of water from the top of the grain bed and tried to drain into the boil kettle at the same pace....

Thanks everyone in HBT for the feedback.

 

[bcryan]

20 minutes seems pretty quick. I usually take about 45 min to collect 6 gallons. Did you mashout? That might help too.

 

[ajf]

Yes, you should sparge slower. With 13 + # grain in a 10g cooler, I would sparge for at least 60 minutes. In a 5g cooler, I would have sparged for at least 90 minutes with that amount of grain

-a.

 

[Yooper]

What they said!

Remember that in batch sparging, you just add water, stir, vorlauf and drain. That "knocks" the sugars into solution so you can get them out.

In continous sparging (fly sparging), you are adding water to the very top of the grain bed, and adding the same amount to the top as you are draining off. This makes sure you don't have any "channelling" from the water seeking the path of least resistance. It gets the sugars out of the grainbed by the process of diffusion. So, you must go slow to avoid channelling and to have the process of diffusion happen. I usually take about 45-50 minutes to sparge with about 4-5 gallons of water.

 

[bbrim]

To add to Yooper's train of thought. Make sure the water you're adding is landing softly so it wont' create a channel. If you pour the sparge water hard on one spot it will channel and only pull sugar from a small area in the grain bed. I have a sparge arm that gently spreads the sparge water out over the surface of the grain bed. I generally take a little over 60 minutes to sparge a 10G batch and my numbers come in great.

 

[JuanMoore]

Did you do a mash-out? On top of what everyone else already said, raising the grainbed temp and using hot sparge water is important for fly sparging. The slow diffusion that Yooper mentioned to get the sugars into solution is aided greatly with higher temps. Also, what are you using to separate the wort from the grains, false bottom, manifold, SS braid? A SS braid won't work very well for fly sparging, and if you're using a manifold the design is much more critical than it would be for batch sparging.

 

[ajf]

^^ He might be young, but he gives good advice.

-a.

 

[Vintage63]

Thanks guys. I use a 15 gallon stainless kettle with a false bottom and round sparge arm. I did not do a mash out (I'm not really even sure how to do that). I was heating the sparge water to about 175 and pumping up to the sparge arm (I am probably losing a few degrees in the transfer too).

I eye-balled the flow rate and tried to match the wort going into the kettle to the amount of sparge water on top of the grain bed (shooting to keep about one inch of water on top of the bed).

 

[JuanMoore]

Mashing out is adding a small amount of very hot (typically boiling) water to raise the temp of the grain bed to ~168-170F before starting the sparge. This denatures the enzymes to "lock in" the wort profile, which is more important for fly sparging since the enzymes would otherwise continue working for the much longer time it takes to fly sparge. The other reason for a mash-out as I already mentioned is getting the sparge to flow better and aiding in the dissolution of the sugars. There are many programs and calculators out there that can help you determine the correct amount of boiling water to add based on the grain bill, mash thickness, and rest temp (beersmith, rackers.org, etc).

A false bottom and sparge arm are ideal for fly sparging, so it sounds like you just need to mash-out, and slow the flow to 1/2-1/3 of the rate you used last time. Hope this helps, and good luck!

 

[Northcalais40]

You can also do a decoction to reach mash out temps. It is fast and reserves water for sparging, important with large grain bills.

Alternatively you can skip the mash out altogether, keep careful notes, and determine if it actually helps your efficiency. I'm not sure it does for me.

The way I understand it, the mash out denatures the enzymes over a period of time. A period of time in excess of the time that my mash actually stays that hot. I sparge a 10g batch for upwards of 1 hour and the stuff is cooled off by then. If I'm outdoors, I can start heating the runoff as I drain so that can denature, so I skip the mash out.

 

[Vintage63]

Thanks again! Stoked already for the next brew!