I have run my new salt water tank for 4 days with tap water to check for leaks, all has been sorted out. I was planning on emptying the fresh water (from the tap, has A tds of 110ppm) and re filling with RO/DI water. A LFS said that i dont have too because I am not putting any coral in,and i can just add the salt to the water in the tank. The tank is a180 gallons with a 40 gal sump. It will take 4 or 5 days for my ro/DI unit to produce that much water. What do you think?