I have a 10 gallon freshwater tank. I have 3 (1 1/2") comets,no real plants. I don't know anything about fish tanks.I have a charcoal filter,a 5" airstone, about 1 1/2" to 2 " of colored pebbles in the bottom and 6-8 plastic plants and a fake rock.and an aqaurium light.I turn the light on at 5:30 am and feed the fish tetra flake food,not too much in the morning. I shut the light off at 8:30 pm. the tank is not in direct sunlight at any time. it is however next to a window. no tank heater. my problem is that the water turns brown and is cloudy after only 2 days even when I do a water change and cleaning.what am I doing wrong? HELP!!!