For what it's worth, hang in there. I struggled with my trates for the longest time. A ton of water changes using RODI water that tested 0. Tried different test kits thinking I had bad ones.Had sand, added skimmer, tried an algae scrubber. Stocked slowly. Only fed every other day. I was really discouraged because no matter what I did my trates ran 10-20 for what seemed like forever. I even battled a cyano outbreak.
I got to the point where I said whats the sense in lugging all of these buckets of water when I am making no progress. I may get beat down for this advice, but what worked for me was I left the tank alone for almost 2 months. I quit being so obsessive over water changes and testing. That was when my tank was about 10 months old. At about the 1 year mark, poof it was like magic and my trates were 0. During those couple months I had major coraline growth and growth of my corals. All I did different was left my tank alone and let it mature. Now I do water changes every 2-3 weeks and all has remained good.