natural seawater good/bad?

[i love fish]

has anybody every used natural seawater 4 their SW aquariums?
when i first started my SW aquarium last yr the IDIOT who set it all up 4 me used natural seawater

saying it was the best thing 4 the fish. I had no experience with SW aquariums and he had years (so he says) and I didn't know about this message board or any other boards 4 that matter.
He even put uncured LR in there!!!!

and said the system will be ready to receive stock in 3 to 5 days.
I now know better thanks 2 books and every1 here......... So back 2 the question........Has any1 ever used natural Seawater? Any problems with it if u have?

 

[mr_x]

if you can get the sea water from about 20 miles out or so, i think it will be fine, but alot of unwanted chemicals/detrius/toxins accumilate at the shorelines.
i'd have that water professionally tested before freely adding it to my reef tank with thousands of dollars worth of livestock in it.

 

[reefkprz]

I dont like the risk of constantly introducing water that may or may not contain freeswimming parasite and new pathogens on an every water change basis. If I were to use natural seawater I would feel inclined to QT the water to prevent such introductions. I like my sterile prefab salt mix.

 

[i love fish]

i totally agree with you guys, that's exactly what i thought.