Hello, Can you tell me if I'm on track? My 75gal. tank has been running for about a year now(FRESHWATER) with a wet/dry & a canister....Right.....14 days ago I drained it 50% & removed the rocks. I then added 2inches of marine sand & the salt, ALSO ADDED a Emperor 400(3 filters total now) & a protein skimmer..I always had a UV Light with the wet/dry, you see. I wondering 'cause I checked my water for the first time today & It's reading for the ammonia:0.50 , nitrite:5.0 & nitrate 40.......IS THIS NORMAL?????? Dee