HELP!! SPS Dying

[Aquattro]

Getting rid of the cannister and drip filter will remove the source of NO3, which will allow your live rock to do it's job. Once you get your skimmer online, nitrate producing filters removed, your rock will eliminate the rest of your nitrates (as long as you're doing regular water changes, not over-feeding, etc). At this point I'd do a few smaller water changes, just because the system sounds stressed already and a big change might do more harm than good.