How to Build a Fly Sparging System in your Cooler Mash Tun

Continuous sparging (AKA fly sparging) is the process by where the brewer continuously introduces water into the mash tun at the same rate they are draining the water from the mash tun. The idea is to constantly wash the sugars away from the grains while not disturbing the grain bed. Many home brewers believe the fly sparging advantage yields higher extraction rates (efficiency) of fermentable sugars from the same pound of grain as compared to batch sparging – dumping all the water in load(s). I let these guys battle it out.

While I don’t have enough evidence to argue either way, one of the reasons we built a fly sparging system in our mash tun is to not have to open the cooler lid to sparge….thus losing heat. Once we get to the point of measuring efficiency, we can weigh in on the great debate, until then, Cheers!

The following instructions are what we did almost exactly. Please follow our guide only as needed.

Directions / Tools / Equipment needed

1. Get your Mash Tun (We use a 50 quart Coleman Cooler) – See our post on How to build a mash tun

2. Tools – you will need the following:

3. Nozzle, CPVC fitting, and hose

  • Using the drill and the step bit, drill ~ a 7/8” hole in the top of the cooler
  • Position it so it is about ¼ of the way across the length and ¼ of the way across the width of the cooler
  • Make sure the underside where the hold will go through is flat, not where the indentations are
  • Given step bit is cone shaped, you will need to drill from both sides
  • You should also continue testing the hole as you go, to ensure a very tight fit

  • Using the screwdriver, unscrew the plastic hinge so the lid comes completely off. Trust me, much easier to work with.
  • Screw the ½ inch threaded CPVC connection (with O-ring attached) into the bottom of the cooler lid

  • Attach the remaining pieces as shown on the left side of the photo
  • Wrap all threads with Teflon tape to prevent leaking

4. Building a Securing the Manifold system (CPVC pipe) to sparge the mash

  • Purchase the following:

  • Using the hacksaw, cut the CPVC into the following lengths:

E. Three pieces 1 in.

F. Two pieces 1 ½ in.

G. Two pieces 2 ½ in.

H. One piece 5 in.

I. One piece 9 1/8 in.

J. Three pieces 14 ¾ in.

  • Drill holes ~1 1/2 inches apart in a row on the CPVC
  • Clean the CPVC out with the brush
  • Assemble as you see pictured below.

Start using it. The goal is to put as much liquid into the mash tun as you are draining out. There is science to this, but I don’t know it….yet. FYI – we also need a rack.