Help with a salt water tank

[mousetap]

Thanks for your replies Mike & George...

It is a 30Gal tank. The store advised me to get about 30lbs of live rocks based on 1 gal = 1 lbs. I didn’t get any test results from them. When I brought a sample to the store, they add some chemicals and checked the colors…and said water is clean. I remember he said that he checked for Nitrite, nitrate and ammonia...

If I did a test now…would they be able to tell…if it is due to an ammonia attack? Do I need to clear the entire water tank before I try out again? Is there anything I could do to prevent this in the future?

Is there any store that you would recommend?