WillMorris said "Vacuuming ok. But it doesn’t get the stuff stuck on the bottom. Plus then you get a chance to inspect roof for any visible damage to alert home owners. 1-204-851-5861 "
Vacuuming is the only way to go. As for the light film of dried dirt on the bottom. Thats most likely an indication the trough is not running true anymore. Likely a slight dip in the trough at that point that puddles there and when the water evaporate you get that thin crusty layer of dirt. After it rains that will happen even if you clean them by hand. But Will I am curious after you are done tieing off. What do you do with the holes from the bracket you used to tie yourself off with . Also you mentioned earlier that you tie yourself off on the steep roofs . What about a normal roof that is ten feet from the ground. Are you tieing off on a roof as such?