The owner doubled the rent. The owner has the right, and apparently Colorado law lets him do it.
But, while $900 a month "may" have been reasonable, $1,800 sure isn't.
Someone moving into town, just establishing themselves, I sort of see a need for a place that takes weekly rent, although not a fleabag, while saving up money for rent and deposit on a real apartment.
But, the equivalent of $1,800 a month?
My wife and I pay a few hundred less than that for a clean, well-maintained relatively large apartment with all the modern amenities, decent landscaping, and decent management.
I wonder if the owner is trying to drive the tenants out, with plans to either thoroughly revamp the building or tear it down and build something else?