Fly Sparge

I wanted to get some opinions on fly sparge techniques

My equipment: 3 vessel system. electric boil kettle. gravity fed HLT into water cooler Mash tun. Pump fed from mash tun to boil kettle.

My questions: Beersmith usually tells me to fly sparge with around 3 gal after adding 2-3gal of mash out water.

- should I empty ONLY 3 gal from HLT into mash tun and drain or should i keep draining water from the HLT to the mash tun and WHEN I hit my pre-boil volume shut off the pump valve?

- I build my water from RO with salts and lactic acid. if I have 5 gal at 168F of sparge RO water how much lactic acid should I put in?

Any help would be much appreciated.

 

I can't help with the acid additions. But for fly sparging (I have never done one) I think you need to balance things out so that, 1) you take between 1/2 to 1 hour for the sparge, 2) do not exceed a certain pH level, and, 3) collect the proper amount of wort for your preboil. I read about this before building my rig and that pushed me to doing batch sparges.

 

I can't speak to the water adjustments, as I really have no experience there.

But from my own experience with fly sparging, you'll get the best efficiency if you can ONLY add the recommended sparging volume to your mash tun. That way, the full volume of liquid that enters the mash tun gets drained out, ideally pulling as much sugar and other compounds out with it as possible, rather than leaving behind some significant amount still in suspension in the fluid still in your mash tun. (At least, that's how I figure it works - I definitely get better efficiency when I don't over-do the sparge volume and leave behind a bunch of fluid in the mash tun.)