I have a 72 Bow-front Reef/Fish tank. A custom made 20 gallon sump with rubble and Cheato by Custom King. I have a Bermuda skimmer run by an Eheim 1260 pump. Works great! 100 lbs. of great live rock. I use 4" filter socks, which I replace every other day. I have a Mag 7 as my return pump. I have a 48" Maristar 2x250 Metal Halides with 2 48" Actinics. I run a Phosban reactor. I have plenty of coral, 3 small clams, a Foxface, 2 Ocellarus clowns, 2 Sand Sifting Gobies, a Potters Angel, and a Christmas Wrasse. All fish are small. I've cut down my feeding, and I do 20 gallon water changes weekly. I use RO/Di water. I use Tropic Marin Reef salt. Salinity is 1.024. All my parameters are good, except nitrates! I checked today with a Salifert kit, and they were at 5 ppm The only possible culprit is the cheato I added a few weeks ago. Any thoughts?