Got a new light fixture today and I also noticed my sand is changing color.

[germanyt]

Just try out the siesta period! lol How long was your light staying on before you put on the new one?

The new light and the brown sand aren't specific to one problem especially since you just got it. It is a common occurrence, I started to get it when I put in white construction sand and then used the siesta period and it never developed into full blown patches.

Its your tank do with it what you like.

Light was on a bunch. What kind of lighting schedule do you recommend. I would expect to see some changes with the new light. Maybe 8 hours a day and keep the blinds on the window behind closed? I was keeping it open all day (very moderate light from outside) because I was concerned that the 2700K light wouldn't keep my grass alive.

 

[germanyt]

I limited the light to 8 hours yesterday. Fed just a couple pellets yesterday and this morning instead of flakes. The sand is a little worse this morning. It looks like it did before I stirred it around vacuuming it. I don't know if you can tell from the picture but it doesn't appear that anything is growing 'on' it. Nothing fuzzy or stringy. It's like it's stained the sand a brown color.

 

[Convict2161]

Your tank is new right? Looks like diatoms which is normal.

http://www.aquascapingworld.com/algaepedia/full_view_algae.php?item_id=79

 

[germanyt]

Your tank is new right? Looks like diatoms which is normal.

Brown Diatom Algae

That's what some others suggested as well. Thanks for the link. I'll bank on that for now and do some more research on it. Hopefully I can clear it up quickly. It's good to know it's not something that's going to kill my plants or fish.