What causes this brown color

[AquaBANG]

I have a 33G tank with a 36W CFL (6500K) this is mounted on the hood about 6'' from the water level. My tank is 18'' deep.

The light has been on for 12 hours a day for about 3-4 weeks now. Only during the last week or so I notice a brown color on my decorations. Its on the tank walls, its on the heater and power head, but it is best noticble on my decarative conch that I have in my tank.

Since the conch decoration is a white color (it used to be sparking white).
http://farm4.static.flickr.com/3129/2454682346_9699905d4d_b.jpg
What could be the cause of the coloration.

Picture taken on 25th Apr
http://farm4.static.flickr.com/3069/2454693336_06c41d40be_b.jpg
Picture taken today 30th Apr
http://farm4.static.flickr.com/3205/2454685318_c096e8f67c_b.jpg
Changes between the two dates
1) 30% water change last saturday with dechorinated tap water.
2) Had a HOB filter and a power filter, the power filter failed and has been decommisioned. the HOB is running 24/7.

[Bobo the Clown Loach]

What are your water parameters?

[jbeining75]

Is that just a normal shell found in the ocean... Sometimes the lack of nutrients can stain the shell.... It might also be an initial layer of algae growing in....

[travie]

I would say some form of algae growth also.

[GreenTerrorNYC]

My guess would be Brown Algae. Algae can be green or sometimes brown, there are many different types.

Here is an article that can give you more info, gives you some possible causes, and cures.

http://freshaquarium.about.com/cs/maintenance1/p/algaebrown.htm

Causes:
# Excess silicates & nitrates
# Inadequate light
# Low oxygen levels Brown algae is a common

Cures:
# Wipe off surfaces & vacuum gravel well
# Use silicate adsorbing resin in the filter
# Increase the lighting
# Stock a plecostomus or several otocinclus This type of algae does not adhere strongly to the tank surfaces, and is easily wiped away. Vacuuming the gravel with a siphon will quickly remove coatings from the substrate. Increasing the lighting will inhibit re-growth of brown algae. As a new tank matures brown algae is often eliminated naturally by plants and green algae competing for nutrients.

Good luck

[angelcakes]

i will agree with brown algae its normally ok to rub off........but on shell im not sure

[AquaBANG]

i will agree with brown algae its normally ok to rub off........but on shell im not sure
I am planning to replace the shell and few rocks with driftwood, so they will be doon gone.

Is that just a normal shell found in the ocean... Sometimes the lack of nutrients can stain the shell.... It might also be an initial layer of algae growing in....
yes, its a normal ocean conch shell. not sure about the inital algae as it was pristine white previously.

My guess would be Brown Algae. Algae can be green or sometimes brown, there are many different types.

Here is an article that can give you more info, gives you some possible causes, and cures.

http://freshaquarium.about.com/cs/maintenance1/p/algaebrown.htm

Good luck
thanks a lot for the link, I have started aeration to increase the o2 levels, I will follow up with frequent wc of 10% each.
thanks.

[jbeining75]

If it is a new tank you are going through the diatom stage and will get a little brown algae. Oto cats will clean it up for you if you want them. i see you have guppys in there....

[Lady Hobbs]

Normal for a newly set up tank. Don't we just love it tho! I waited for my tank to get better established then had to bleach the rocks out, soak them in dechlorinatored water and add them back to the tank. And wipe the walls daily with paper towels. Pain in the neck but it does eventually stop when established.

[GreenTerrorNYC]

Glad i could help, i am currently establishing a tank, so i am expecting the same, i will keep you posted.

[Kayla-Bug]

This is completely normal. Like most said, newly established tanks will get brown algae. I had it in my 24 gallon and all I did was wipe it off and my snails have been doing a great job keeping it away. Also Mollies are good at getting rid of algae. I did read somewhere where it said it was diatoms or something like that. But still. Completely normal.