In all grain homebrewing you take crushed grains and soak them in water to release it’s sugars/starches, this first step is called mashing. When you finish the mashing step, you drain the water from your mash tun, the vessel you are mashing in and you have the left over grains. Inside of those grains are left over sugars that haven’t been extracted and remember the point of mashing is to release the sugars, so anything left over is wasted. Here are the two most common methods to extract the residual sugars from those grains and get you closer to saving money and making you a better homebrewer.
This is the simplest of sparging methods and requires no extra equipment. To capture the left over sugars in the batch sparge method you lauter as normal and completely drain the mash tun, close the spigot and add another round of heated water usually 1.3 quarts per pound of grains. You let that hot water sit in the grain bed for twenty minutes and then recirculate and drain again.
This method is simple and less labor intensive but its main draw back is not extracting enough sugars/starches as the more advanced fly/continuous sparge method. With this method you should collect around 66-70% of the sugars in the grain.
Hermen uses the batch sparge method in his video on all grain brewing.
Continuous Sparge aka Fly Sparge
This is the most efficient of sparging methods to capture all of the sugars from grains. To capture the left over sugars here you recirculate and begin to slowly drain your wort. When the wort is an inch above the grain bed, you slowly begin to add heated water to the grains. The goal here is to create a “wave” of water that pushes out the remaining sugars by creating a steady stream of water passing through the grains allowing the new water to collect and push down the sugars left behind.
This is the method I use and can become tedious. When I do this I use a colander and a 1 cup measuring cup to slow and evenly add the heated water to the grain bed. Yeah it takes a while and is a lot more labor intensive than the batch sparge but in the end its worth it. I consistently get from 72 -74% of extracted sugars sometimes even more if I’m lucky.
To cut down on the labor part of this you can do a internet search for “fly sparge arm” and you can either buy one or DIY it.