I would persoanlly be concerned about the CLR leaves trace chemicals, but i hope others would chime in with thier opinon!
Since you have nothing in the tank yet, I would say Break it all down, rinse that tank with Hot water many times and start all over!
Pick up some Live sand substrate 1-2 inchs and probably some Live Rock, 20 lbs or so, get rid of the undergravel filtration, Mix your water RoDI and salt to about 1.25 ish, let this cycle for about a month testing for ammonia all along , you will see it it spike then lvl out to 0! if you only plan on having fish, you probably have good enough lighting!
Welcome to the Hobby!