This will cause a slower fermentation. You should definitely pitch at a higher rate: 2-2.5 lbs.
1HL = 26.417 US gallons. As such, it would be 50-100g per @ 26.5 gallons.
You want a good strong fermentation so you should go on the higher side. EG for 250 gallons, @1000g+. There is a high range due to the varying aspects of the fermentation process (ingredients, sugar content, fermentation temp, etc). You cannot really have too much yeast for distilling.
The alcohol tolerance is @ 20% and the dosage rate is 25-50G per hectoliter.
The loss in yield with Hammer mill vs. Roller mill is a tough one. 100% liquefaction depends on particle size, temperature, time, and pH control. If the particle sizes are a little larger than recommended sieve sizes, you may be able to overcome the problem by extending the liquefaction time and perhaps use more vigorous agitation such as a lightning mixer with shearing blades.
The professionals use HPLC because they must have exact data. You can come close to estimating expected alcohol yields, from the liquefied starch, by using a Brix hydrometer:
Brix X 0.5 = % alcohol ABV (close) or Brix divided by 2 = % alcohol.
For our WLP050 Tennessee Whisky liquid yeast, there are several options:
1) 8 liters of yeast to achieve the same pitching rate as the 2-500 gram packs; this would achieve the same fermentation speed.
2) Our brewery size 10HL pitchable batch. This is more economical, but will ferment 2-3 days longer than option number 1
3) 1-2 liters of yeast into 100 liters for 1-2 days, then top up to 1000 liters.
For those seeking to go “higher end,” we would suggest that you try WLP028 Ediburgh Scottish Ale Yeast & WLP050 Tennessee Whisky Yeast.