Looks like you're in stage 4/5 of the cycle. Diatom blooms, cyano outbreak, and possible hair algae is right on the horizon. With high nitrates such as you reported you will see the green film algae develop on the rock work. This is inevitable but will ultimately be replaced by coraline, provided the water parameters and lighting are correct. Once your tank has matured say in about 6 months to a year anaerobic bacteria will have colonized deep in the rock as well as the sand bed. These are the nitrifying strains that consume nitrates and convert to nitrogen gas and nitrogen sulfide. As a result many mature tanks require far less overall maintenance and water changes compared to new tanks. Repeated large water changes the addition of macro algae such as chaeto are the only ways to easily and effectively lower nitrates to a more manageable level.
The most important thing to remember is have patience. With time and staying on top of the water chemistry you will have a beautiful reef tank that you can enjoy for years.