Is $50 late fee per day legal?

[Thomas Wang]

Is $50 late fee per day legal in Colorado? I bought a rental that came with a lease that says $50 late fee per day if rent is not received after 3-day from the due date. I need to serve a 10-day notice and try to figure out how much late fee it include along the unpaid rent. This tenant now late for third time in 6 months and feel that I need to start enforcing the terms of the rental contact. Thanks