I've my had 29 gallon tank running for almost 3 months now, and this week I've all of a sudden got brown spots on my glass and my sand is turning brown. I have an Odyssea 24" 48w T5HO light. Running these for 10hrs a day with no C02. Is this my problem? If so, why is the algae just turning up now? I'm dosing Flourish twice a week, if that helps any. Others have said the brown is just something that happens in tanks that are starting to mature, and will go away on it's own. What do you guys think?