I'm continuing to have Nitrate problems with my corner tank. I did WQ test tonight, and Nitrates were either 80 or 100ppm.

Here are the other tests:
Ammonia 0
Nitrite 0
Kh 12
Ph (after I put buffer in) 8.24

Weird things: I'm never seeing any spike in Nitrites, and not in Ammonia since I had something die in the tank a while back (a couple of months ago).

Other weird things:
My wave tank (the other tank) is:
Ammonia 0
Nitrites 0
Nitrates 0
Kh 15
Ph 8.24

Both tanks are 90/92 gals. Both have a relatively equal # of fish. I feed both tanks exactly the same amounts of food, both in terms of fish food and coral food (coral food consists of DT's, LiquidLife Zoo plankton, and oyster eggs). The corner tank (w/ the high Nitrates) has about 35 - 40 pieces of coral. The wave tank has around 20 - 25 pieces. The corner tank has a sump and Tunze skimmer. The wave tank does not (no sump, Prizm skimmer). The only other major differences I can think of is I have clams, Zoo's, and Xenia in the wave tank (0 Nitrate), whereas I have mainly more "higher end" corals in the corner tank (80 - 100 ppm Nitrate). I did about 20 - 30% water change on the corner tank about a week and a half ago.

Any ideas to 1) what is causing the high Nitrates? 2) when I should really really start worrying (like maybe now?) about the Nitrate level, and 3) ideas to reduce the Nitrates would be greatly appreciated.

Stephen