I have been told that water from the gulf or any ocean cannot be used for aquariums. Does anyone know if it can be used for monthly water changes? I was told it has too many organisms for a tank, but this was from LFS that wanted to sell me salt.
I used ocean water from 1966-93 when I lived in Palm Beach County in my FO and Reef tanks. I used to collect it on the incoming high tide in the Palm Beach and Jupiter Inlets when I didn't have a boat available. No problems at any time. If you are raising larval stage fish however, there are a lot of predators waiting for them in the water and it is best to use a net mesh of correct size to strain out the nasties.
I knew a woman back in the early 70's in Gainesville, Fl who drove to the Gulf and transported water back to her SW aquarium. Inhabitants were mainly the hitchikers she brought back or things collected along the shore, bivalves, live rock with barnacles, etc. No skimmer, no DSB, etc. etc. Pretty primative, but she kept things alive and it was about as natural as things can get.
I'm not familiar about water from the Gulf, but I do use natural salt water from the Pacific for my tank with excellent results. The water is from Catalina Island and the company's website is Catalina Water, and is explains their procedure for NSW. HTH.
I've used Ocean water for my water changes before with no ill side effects. I just wont do it if there has been a sewage spill, rain storms, or peligro signs on the beach.