[danny zubot]

It doesn't help that you salt was adding to the problem but I would begin by getting to a proper resolution for this issue. How much live rock do you have in the tank, and how much flow? I do a %10 water change every 3 weeks on my 54gal. (65 gallon with sump) and my nitrates never exceed more than 10 or 15 ppm, which I consider accetable after that alotted time. Your feeding habits and the amount of live rock\sandbed will determine how well your system can effectively denitrify your water. I agree that large water changes can be stressful to a tank so I am minimalistic in this regard. Furthermore, this is only what I have noticed from my experience with smaller tanks, consider adding more live rock to house nitrifying bacteria and see if you notice a difference. A tank that can heal itself is much more healthy than one that requires a doctor.