I set up my 120g tank last night. The substrate I used was pea gravel that I bought from Lowes. If you've ever seen the stuff there is a lot of mud in the bags. I rinsed it the best I could. Once I started adding water to the tank it became a little murky as I expected. There are not any particles per say just some cloudyness. Its hard to explain but I can see it churning around. The other info you should know is that I added seeded filter media from an established tank and I dosed the tank with ammonia last night. I haven't taken a reading yet today to see whats going on. Since I have the seeded media I didn't know if I should do some water changes to try to clear up the water or give the 2 AC110's a few days and see what happens. I doesn't appear that the water is getting much clearer as I can still see the murkyness. I added Prime last night when I filled the tank because I had cleaned some of the rocks in the tank with a bleach solution. (I am on a well so no chlorine) So I didn't figure I would get an accurate ammonia reading last night so I just added some ammonia and left it. I am getting ready to check the parameters tonight and then dose again to see how far along I am in the cycle with the seeded media. EDIT I just checked my parameters and it was .50,0,0. I dosed the ammonia and got it up to 1.0. Since it has been 24 hours since I added the Prime I should get an accurate read tomorrow on how my cycle is going.