how do you know when to stop fly sparging?

[glang]

I'm new to AG brewing and I've done about 4-5 batch sparges. I'm going to try my hand at fly sparging tomorrow and feel like I have a pretty good set up to do so. My main question is, how do you know when to stop fly sparging?

Beersmith has me mashing in with 7.8 qts, mashing out with 4.3 quarts, and fly sparging with 1.3 gallons (I do 2.5 gallon batches). Do I fly sparge with 1.3 gallons, then just stop when I hit 1.3 gallons and let the rest of the sparge water run through the grain bed and in to my boil kettle? Or do I just keep fly sparging until I hit my pre-boil volume? I know you're not supposed to let your gravity fall below 1.008, but I don't own a refractometer. Do people pull samples and use a hydrometer in a test tube?

 

[crispbrew]

Just sparge until you hit your pre biol volume since this is your first time. You can stop sparging when you hit 1.3 gallons and let the rest drain and you should get your pre biol volume, but with out knowing your system you might come up short of your pre boil.

The whole letting your gravity fall below 1.008, I wouldn't worry about it unless you are doing a small grain bill for a low gravity beer.

 

[insanim8er]

This is one of those things that you'll see everyone does it different.

Some fly til they hit volume. Some will measure the water. Some will sparge until they hit a particular gravity. Some will sparge until their sparge is 1.010 or even as low as 1.007.

Some will fly sparge with out doing a mash out. Meaning they vorlauf then they drain their wort into the BK as it's going, they start the sparge 2" above the bed.

Your unlimbers look pretty good. You want to get about half your volume from your first runnings.

I use a refractometer, but you can stop the sparge, test a sample and temp correct, then continue... Kind of a PITA.

 

[Spartan1979]

I sparge until I hit my volume or my pretreated water runs out. Usually the former.

 

[Kingbogart]

For your first time I would measure and then stop when you hit your preboil volume. A majority of people that continue sparging past their preboil are working for extra efficiency. You can continue collecting until the sugar drops to the 1.008-1.010 range and then just plan for a longer boil. Most people would prefer to pay a little more in grain and leave some sugars in the tun than to stand around boiling for an extra hour, but whatever you prefer is fine.

I do take a number of hydrometer readings throughout, I cool the samples using a small ice bath to the calibration of the meter. I usually take a first runnings reading, and then a reading when I've collected my preboil volume to see how much sugar is left in the tun, and a mixed reading in the kettle before I boil so I can determine if I need to make adjustments. Such as extend the boil, add dme, or add water.