Fly Sparge Amount in BeerSmith

I'm baffled.

1). How do you figure fly sparge in Beersmith? I see batch info but???

2). Also, if I preheat a 5 gallon Igloo as a HWT using boiling water, is there a way to compute what temp the actual sparge water should be to get it to 170?

Probably obvious but...

Thanks!

1) You fly sparge until you hit your boil volume and/or desired pre-boil OG.

2) Don't use boiling water to preheat an Igloo. It will probably warp/damage it. Also, preheating the MLT is to prepare for the strike and mash in, not the sparge. After the mash is complete, your grain bed should be around 150°F or so depending on your mash temp. BeerSmith gives you a temp (around 190) for the batch sparge water to get the grain bed up to 168°F. If you are fly sparging, you would use 169°F water for your sparge.

I think you are trying to combine processes and it is confusing you...... Or I may be confused.
This advice comes with a limited warranty of 1 year or a rise of 1°F, whichever comes first!

Thankjs. That helps a lot.