I am in agreement with the ...

I am in agreement with the others on a few of the ways to know the concentration of your slurry. If this was my operation based on the information given I would do and average dry weight delivered over time as suggested. You could also have a weighted lime vat and a water meter. This would give the weight over time versus water flow over the same period. You could also weigh a sample of the slurry many times to get an average pounds per gallon of the slurry. Subtract 8.34 lbs/gallon water weight = lbs/lime pergallon calculation based on sampled volumes. Many was to accomplish this task.