Is it required that bank cylinders that are immobile be hydro tested every five years?
You are in FL. You will need to do one of 2 things:
1) A permanently installed pressure vessel will need to comply with FL State boiler code, this would basically mean you have engineered drawings, ASTM vessels, all piping complies with engineering codes, has been installed by someone licensed as a plumber/boilermaker for pressure vessels, and the building inspector has signed off.
2) a quasi permanently installed DOT cylinder "subject to federal or state inspectors" per Chapter 10. Section 1001.1 - is an exception to FL mechanical building code. These require VIP and hydrostatic requalification every five years.
The chances of you getting cited for violations of either compliance path are probably non-existent absent an explosion or injury.