Brown murky water

Question
QUESTION: hey david. so i just got a 55 gal aquarium from a guy off craigslist. (great deal, $125 for everything) anyways i brought it home and set it up. before i put anything in it at all its water had already turned into a dark brownish color. all the water readings were neutral for a week so i went ahead and put 5 inch long cichlids in it. (2 jack dempseys, 1 midas, 1 green terror, and 1 jaguar) don't worry, its a grow out tank.
any ways so no matter what i do the water is still dark brown. I tried doing a 3 gallon water change daily and it didn't help at all. i recently read something that said to try to not do a water change for a while and let everything settle so thats what i'm doing now. but i think that the water is just getting murkier. please do you have any advice?

ANSWER: Hi Rob:  What kind of filter are you using??? What are you feeding??? how much light does the tank get per day??? dave

---------- FOLLOW-UP ----------

QUESTION: i am feeding hikari gold twice a day. i have a whisper filter (i think for 60 gal)It gets a little direct sunlight, not too much.
But i don't know if any of this matters, because the brown water was a problem on the first day before i had put the fish in or started the filter.

Answer
Hi Rob: Thank you for getting back to me.  I would use a water clarifier that can be used for both ionic and biological particles. Kent makes very good water clarifiers. The clarifier will clot all of those floating particles together and cause them to be trapped by the filter.  I would also put a polishing filter pad in the filter for the time being. If you have not changed the carbon or other filter media then I would do so as well.  If the tank came with used gravel then I would definitely make sure that you clean it with a gravel vacuum.  Do you have driftwood in the tank???? that can also cause the water to turn tea colored and even black.... keep me posted dave...