NEW to Salt - Help, setting up a 90 gal.

[mr. limpid]

Quarantine tank separate tank to keep anything wet in to observe to make sure creature is healthy or 6 weeks to make sure any parasite is dead. Even clean tanks may have parasites on there fish. They come from being in contact with other fish or in water column or stuck to anything wet. This happen even B4 the LFS get the fish or rock or etc.

 

[beaslbob]

FWIW I recommend you start any tank with plant life then do the rest. In saltwater that means macro or other algaes in a refugium or algae turf scrubber.
You have nitrates for two reasons.
1) new tanks cycling with plant life like macros will have an initial nitrate spike as the plant life is consumeing ammonia while the bacteria is building up. This is especially true in tank where there is an existing nitrate source like substrates with some organics in it. Or possible used holy rock. Then as bacteria build up the macros will consume nitrates for nitrogen and nitrates drop down. Usually in a few weeks with sufficient algae.
2) In established aquariums with little plant life you don't have the nitrate consumers there to keep nitrates low. So add algaes.
I would also consider using common FW mollies you aclimate to salt for an initial fish to get the cycle started. I single male will do. And don't add any food for the first week. If you can get one acclimated and living for a few weeks you are will on your way to the more expensive marine fish.
my .02