Mashing and Sparge question

I have jumped to all grain about 10 batches ago. I have been having trouble at the mashing and sparging point I think. I use a 10 gallon igloo water cooler as my mash tun and fly sparge with gravity feed. It seems I am always getting more wort than my beersmith is calculating. Last batch said I should have about 6.5 gallons to boil for a 5 gallon recipe. Turned out to be just about 7.5 gallons. I used the exact amount of water in the mash tun and sparged with the exact amount recommended. I did boil it down to my 5 gallon mark to ferment and hit the OG spot on. Just doesn’t seem like I am doing something correct.

The one thing you can absolutely control is how much wort you collect.  To learn the "water math" of your AG system, I recommend you collect exactly what the Equipment Profile calls for and shut the valve.  And do everything as prescribed, and take accurate measurements, etc.  Boil as needed to hit the gravity target. 

If you end up with four gallons, so be it.  But now you know if what you're collecting is correct for the typical 60 or 90 min boil.  Check all the entries in the Equipment Profile against what actually happened and enter true Measured Results.  Based on that, you can now adjust on the following batch, dialing it in closer and closer until you're usually within a few points of your targets each brew. 

You want water leftover in the system. The tail can contain tannins which don't make good beer.  Besides that, it's much better to have too much than too little.

True, and if you want to, the leftover low-gravity wort (usually b/t 1.010 and 1.020 here) can be beefed up with DME, and then canned in a cheap pressure cooker.  And any leftover boiled wort could be used as well.  Just get the OG of these leftovers to 1.035-1.040 and it's great for starters.

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