pneumatic Offload questions Sand/salt

HELP!!! I need some advice from EXPERIENCED drivers who have delivered sand and salt.
I started a new position with a pneumatic dry bulk company back in February. I have BEEN doing cement and fly ash with no MAJOR issues.
However, I was offered a position in the company for more money and a new truck doing sand and salt.
The "trainer" I went with was pretty good at explaining and teaching the in's and out's. But, my question has to do with offloading. We went to a place that had an APPROXIMATE 400 ft run. There were 5 90' turns that I could see. and the pipe went straight up the side of the silo for AT LEAST 300 FT. He had the RPMs at 1250, full air and aeration and was maintaining a pressure of 12-13 lbs. But it took over 3 HOURS to offload. Now when we got there, the operators comment to me was, "blow at 8lbs or you'll be here all day". Now, being in "training" I have to do what my "trainer" says. But, 3 + HOURS seems really excessive to me to offload. But, with my trainer, I really couldn't experiment to much. We had NO issues and did NOT plug up, so all-in-all, everything went smoothly. It just took forever(?) to offload. Would you experienced guys, given the scenario, consider this "normal"?

Now, at this point I should let you know that I have 6+ years experience on the Liquid Bulk side (HAZMAT) so I am VERY familiar with maintaining pressures and long/short runs and adjusting as necessary. And I have NEVER spent anywhere near that amount of time to offload UNLESS there was some issue.

Now, the SECOND day we went to deliver sand. Now these were small tanks and the runs were MAYBE 50 ft. Literally out the trailer, our 20ft hose and into the tank which were MAYBE twice as high as the trailer. But, he's running the RPM's at 1250, full line air and aeration, and again 12-13 lbs pressure. And it's blowing dust out the tank vent everywhere. Now the operator DID NOT seem concerned, but that RPMs seemed excessive to me considering the short run. And blowing the dust everywhere???? AND one of the tanks had the spout above the tank, so you could actually SEE the product going into the tank. and it looked like to ME that it was about 90% air. It looked like we were moving more air than product.
ANYHOW, considering the WEIGHT of both these products and the "runs", does this seem "normal" to you experienced guys???
I go on my own on Monday, So I will be playing around with things, BUT???
Please let me know what you think or any usefull suggestions?

Thanks!

 

Thanks Guys!!!
That's what I was trying to find out. If the "times" are Normal, then I'll just play a little and make sure everything stays flowing and go about my day

Thanks!!!