Fly Sparging vs. Batch Sparging
First, let's give you a little background on what the two types of sparging are. Fly sparging is the process of using a sparge arm, or any device that allows the water to sprinkle over the grains in the mash tun. A sparge arm is used to prevent the channeling of the water so that the highest extraction rate can be achieved. The brewer's goal is to match the flow of the water going into the mash tun with the flow of the wort going into the brew kettle. You want this part of the process to take about 60 – 90 minutes so that you get the best extraction rate. You do not want to open your spigots all the way because the liquid will drain from the mash tun too quickly and you will end up with a very low starting gravity (S.G.).
You do want to pay attention to the flow rate when you fly sparge. Keep a constant eye on the amount of wort being collected and adjust your flow rate if you are collecting too quickly or too slowly. A lot of all grain brewers continuously monitor the runoff gravity and cut off the sparge when it has reached 1.010 to avoid leaching of tannins and other undesirable grain compounds.
Batch sparging is the same idea as fly sparging, but you do not need a sparge arm. With batch sparging, you completely drain the mash tun of liquid. Then you add more water to the mash tun and stir. We recommend replacing the lid and waiting 30 minutes before you drain the newly added water. After the 30 minutes, you drain the wort, and begin the boil process.
Batch sparging allows you to save time because you can open the spigots all the way. You do not have to monitor the flow rate as it does not matter. And, you do not have to take specific gravity readings as the gravity will not change throughout the process.
In the past, brewers stayed away from batch sparging because the efficiency rate was lower compared to fly sparging. Today's grains are modified specifically for brewing, and they do not appear to have the same issues as grains did years ago. If you find that your starting gravity is turning out a little lower then you expect, add a ½ pound to a pound of base malt to your recipe.
Most of the all grain brewers at Midwest will use the batch sparging method because it is so much quicker than fly sparging, and you don't lose any efficiency. Most of us started with fly sparging because making beer was done that way for several years. Frankly, it had to be done that way due to the poor conversion ratios you would get with the grains at the time. Now, the difference between the two methods is almost identical. It might cost you an extra dollar to make an all grain batch using the batch sparging method, but it is unlikely that you will even need to use the extra grain.
Try the batch sparging method a few times and see what your results are. If your numbers are low after a few tires, then go to fly sparging. The more you all grain brew, the higher your specific gravity numbers will be until you finally reach the maximum efficiency that you will get out of your system. At that point you are working on consistency between batches as far as the efficiency numbers are concerned.