Brown spots forming in the tank!

[razzledazzlebee]

I have had my 2" Figure 8 for only 3 weeks, and am have a lot of brown spots forming on the plants, decorations, and even glass. I keep just the single fish in a 12 gallon tank with a full hood and a built in Penguin System with a Bio-Wheel.
I have been doing 25-50% WC 1-2 times per week, and have been doing water tests quite frequently. Here's the data:
Brought the fish home on 9/3/07 and it was in good shape before that (8.0 pH, 0 Am, 0 Nitrite, .25 Nitrate). Salinity has stayed at 1.008
9/5 pH= 8.0 Am= .50 Nitrite= .50 Nitrate= 5.0
I then did a 50% WC
9/6 pH= 8.0 Am= .25 Nitrite= .50 Nitrate= 5.0
9/9 pH= 8.0 Am= .20 Nitrite= 1.0 Nitrate= 5.0
Did a 25% WC
9/12 pH= 8.0 Am= .20 Nitrite= 1.0 Nitrate= 5.0
9/16 pH= 8.2 Am= .25 Nitrite= 1.0 Nitrate= 5.0
Started noticing brown spots. Did a 25% WC
9/19 pH= 8.0 Am= 0 Nitrite= 0 Nitrate= 0
Did a 50% WC. Took out all decorations and plants because of the brown spots.I cleaned them with hot water and scrubbed with my hands (no soap)
9/20 & 9/22 pH= 8.0 Am= .25 Nitrite= 0 Nitrate= 0
Brown spots are starting to appear again!
These spots are brown, not green like algae. I don't know what they are. I have been feeding what she can eat within a 5 minute period or when her tummy gets full, not much seems to be wasted. I feed her every day except Fridays, and give a variety of frozen krill, blood worms, or clams. Once a week I bring home snails and ghost shrimp. On those days I don't give her other food since she eats those quickly.
What is the brown stuff and how do I get rid of it? It wipes off the plastic plants easily, but the cloth plants remain stained.
Why is the brown stuff forming?
I am confused about the sudden drop of the levels. I was not pleased to see Ammonia and Nitrites showing up (I used Bio-Spira twice, and the tank appeared to be cycled pretty well when I brought the fish home. But for everything-including Nitrates to disappear is alarming. I changed the filter tonight so we'll see if that helps...
Any advice would be appreciated! Thanks in advance...

[taureandragon76]

Sounds to me like you got brown algae in your tank, here is a link about it
http://www.plantgeek.net/article_viewer.php?id=9

and another
http://www.thetropicaltank.co.uk/algae.htm#brown

[Troender]

What do you use to test the water? Those fluid tests or those strips?

[Boxermom]

Brown diatoms. Normal for a new tank and they go away as the tank matures (mine usually take about 6 months). Just rub them off with your fingers.

The ammonia and nitrites are of bigger concern. You should be doing daily water changes until the tank finishes cycling. In addition, I would recommend using Prime as your water conditioner if you're not already and treat for the entire water volume of the tank, not just the water being changed, to help detoxify the ammonia and nitrites.

[Myaj]

I agree with Boxermom. For the first 3-6 months or so you'll have brown diatoms, its just normal for a new tank. One day they'll go away and you'll forget you ever had them. They aren't pretty, but they don't hurt anything.

Stop scrubbing it off though! Your bacteria is trying to establish on the surfaces, and by scrubbing them, you are killing the bacteria, which is why you got more ammonia and nitrite readings.

Keep doing your water changes and let things stablilize. No more scrubbing!

[Pufferpunk]

Yeah, just clean the front glasss, so you can see in.

[razzledazzlebee]

I use the liquid tests.
Good to ear the brown algae isn't a menacing sign.
So, I should use more water conditioner to help the levels? I put one drop per gallon of water changed...

[Myaj]

The only "water conditioners" I know that will actually help with ammonia and nitrite are Prime or Amquel, both of which have instructions on the bottle for regular declorinating use and for using to treat a tank with ammonia or nitrite readings. What are you using? If its Cycle or Stress Coat or something like that, its likely doing more harm than good.

We are saying you need to do water changes because ammonia and nitrites are toxic, so you need to keep them diluted as much as possible until your bacteria recovers.

[razzledazzlebee]

That's fine, but right now I have 0 of all the levels...
Should I feed the fish less often?

[spoot]

Nothing seems to help much except time. You'll notice sometime around 4-6 months that there is less and less. Then one day, you'll find it gone completely and a smile will be had.