This thread piqued my interests, especially because I use nitrates as a calculation for water change intervals. First I want to state some background about my reef setup. My systems are unskimmed and unfiltered, so nitrogenous wastes from crabs and various metabolizing organisms (including the minute amounts from corals not fixed by zooxanthellae) are processed solely by the surface area of LR, and the current provided in my design. My small reefs function within a nitrate clearance range because there is no where else for it to go, as it builds up over two-three weeks I take it out with large-volume changes. All my inhabitants have adapted to the changes, and I match water params perfectly (sg, temp) at each interval. The system in question is about 1.7 years old.
I commonly use about 3-4lbs LR per gallon in my unexported systems (with no filtration I need extra surface area) and I know its time to change when nitrates are up to 15-20 ppm. Freshly after a water change, they would be about 1-5 depending on the regularity of last month's feeding schedule and its accumulated particulate matter (future nitrate). I have done no studies concerning natural N03 levels, so for quite sometime I didnt know 15-20 was bad, actually I thought it was quite good considering a great LFS display ran at 20-30 continually! My question to Mike and others is: what forms of stress have you seen in the corals/inverts that are subjected to the increased nitrate levels? As far as I can tell, my hammer corals and SPS (should be touchy in an unbalanced system right?) are doing well, they have measurable calcification that states they are plating just like they would in an average setup. However, I have not had success with fox corals and purple tunicates over the long haul, maybe this is a sign of such stress. How can we measure stress in these individual specimens when they are subjected to params outside those of NSW>?
Very nice thread reefguide, archive material!
Brandon