Is this possible?

[gobytron]

different spectrums will encourage different algae...
Though I switched from MH to the exact same t5 setup as you for a week and didn't see any change in my parameters...

Any chance of a pic of this algae....brown and harder to get off than coralline?

[DiverDude]

How old are the bulbs in your Tek light ?

If you don't know or they're 10+ months old, I'd start by changing them.

[tony_3a]

Yeah the algae is actually purpleish brown, and it looks more of a slime or like a coating and its not stringy at all, I will try to get a pic tomorrow, and the bulbs are only about 5 months old.