Trouble understanding sparge temp and beersmith

My last batch efficiency was poor. (only second AG batch) I then realized that I probably sparged at too low a temp. Somehow BS had me sparging at 168. Don't know how that happened.
So, I am looking at the Adjust Mash Temp tool. I plug in 0 for water volume assuming I have drained the mlt after mashing. I plug in 10 for weight of grain. I assume 154 for current grain temp. I guess 5 lbs for weight of mash tun (don't know exact at this point). I put target grain temp at 168 for the double batch sparge. At this point I assume the calculator ought to tell me the water addition temp needed, but it does not. It is blank waiting on me to plug it in. But that is what I'm trying to figure out in the first place.

Where am I going wrong?

I don't think the adjust mash temp tool will work with a zero for water volume, it's more for correcting the entire mash volume if the temp is off. Use the strike/infusion temp tool to choose a target sparge temp and find the correct strike temp, then plug that in to the details section of your mash profile so it comes up on your brew sheet. With the grains already in the 150's and no water in the tun, the mash water will only cool a few degrees.

That being said, I don't think the sparge temp contributed to your efficiency issue. People have shown that sparging with room temp tap water doesn't really hurt efficiency. Without knowing more about your recipe and process, it's hard to say what caused it. How was your crush? Did you stir the grains really well both when doughing in and when adding the sparge water? Is your thermometer accurate, and did you hold good mash temps?

I have been "tinkering" with my mash/strike temps in BS recently.
When I brewed last I added 3 degrees to my desired mash temp in the software and after striking, I was right on the money.
I have not read too much on BS but I have noticed other brewers talking about strike/mash temps being off a little when using the program!
All things considered, I like BS!

Thanks. I'll play around with that. I haven't checked the thermometer for accuracy, but the stirring etc., was all good. I was supposed to have 154 for 60 minutes. When I opened the MLT it was reading 151, which I took to be pretty good. My lbs ground the grain, so I hope that was good. I have noticed that others on the forum talk about sparging with very hot water. They seem to be shooting for a grain bed temp of 168 or so, and adding 185 or higher on the sparge. I'm new, so I don't know if it would have made a difference.

My bet for the low efficiency is the crush from your LHBS, but I'd still reccomend calibrating both your thermometer and hydrometer before your next brew day. When batch sparging with no mash-out, a grain bed temp of 168 during the sparge is a good number to shoot for (keeps sugars liquid without risking tannin extraction), but as evidenced here - Cold Water Sparge -it's not that critical and doesn't really effect efficiency.