The single stainless steel filter/braid in my low budget Mash/Lauter Tun (MLT) doesn't lend itself to Fly-sparging. I've read this type of filter design will cause channeling and thus a poor extraction efficiency. Solution, "Batch Sparging".
I first read about the method (and MLT design) in Denny Conn's Cheap 'n' Easy Batch Sparge Brewing article. A super simple concept which fit well with my low tech brewery. The idea, mash at desired thickness for desired length of time. Drain mash tun completely. Add a larger volume of hot water back into the MLT and rinse residual mash sugars by stirring and draining a second time. Done.
Through trail and error, I've managed to fine-tune my Batch Sparging technique, it works very well for me. Let me share...
I use my brew software to play around with mash thickness until I get a nice round water volume # to strike with. My mash thickness ranges between 1.2qt/lb and 1.35qt/lb. Side note, this is strange, I formulate recipes in Metric but use Imperial for mash thickness and temperature readings. I don't know why. Anyways, I strike and wait (mash) for 1hr. Strike temps are dependent on a desired mash profile (Thin, Medium, Malty), again determined by my brewing software.
When the hour is up, I mash-out with a volume of hot (boiling) water equal to the grain absorption which occurred during the 1hr mash. This mash-out volume is, you guessed it, determined by my brewing software. The strike volume - grain absorption + mash-out volume = half my desired total volume into the boil kettle.
I drain around 2-3, sometimes 4-5 litres from the MLT and pour this back on top of the grain in the MLT. This recirculation is called "Vorlaufing". You're essentially setting or slightly compacting the grain bed inside the MTL so that it, as well as the stainless steel line, can filter the grain from sugary water now called "wort", as it exists the MLT.
When the recirculation becomes somewhat clear, the flow of wort is directed to collect in the boil kettle. The MLT is drained completely, this process is called "Lautering". The collected volume is called your "First Runnings". Your first runnings should be roughly half your desired pre-boil volume.
With the drain valve shut (LOL! Made that mistake more than once!), the MLT is filled with sparge (rinse) water. Since the grain bed is quite warm at this point, the sparge water doesn't need to be boiling. I find around 185F results in a grain bed temp of 170'ish; perfect for dissolving remaining sugars into the water solution. This quantity of sparge water is equal to roughly the second half of your total desired pre-boil volume. The mash won't really absorb much more at this point. Stir the mash well. Recirculate (again) and drain the MLT (again). This is called your "Second Runnings".
I have found that if I split my second runnings in two, adding the sparge water in two parts with another good stir and a third recirculation in between, my extraction efficiency jumps about 5%. If you think this more bother than it's worth, add an extra handful or two of malt to your grain bill.
That's it! Easy stuff. Cheap, low tech and efficient... that's how I role.
You can watch Don complete the process: Here