If you have seaweed available 24/7 make sure you get any piecies that break off. If your fish do not eat it, it will contribute to Nitrates as well. Also if you did a big water change did you add TLC or Stability to help quickly replenish bacteria. Every since I have been using stability and Purigen I have been able to keep my Nitrates below 5ppm (woriking towards that undetectable range), before that I was always 25-30 no matter what I did. I have not changed my feeding habits. They are fed Seawead is placed in the tank in the morning and the evenings, and they get small feeding everyday with a larger feeding every other day (use a variety of foods). Also, use Kalkwasser with Vinegar. This mix helps feed the Nitrafying bacteria. Kalkwasser, Purigen and Stability this combination along with alternating % weekly water changes 10%, 15%, 20%, 15%, 10%, etc. I have been trying to get the system to manage itself when it comes t the ammonia cycle. I think I was originally doing big water changes to frequently and was hampering the ability for the Nitrafying bacteria to do its job. I also stopped using my UV sterilizer. I use a Phosphate reactor to keep my Phosphates undetectable. I am new to this hobby but, I finally feel like I am not up against the wall. Progress is finally being made. Everyone has different things that work, but my Corals and Fish have never looked happier. Sorry if these came off like a small rant