How often do you change out T5's?

[Paaxil]

I have had my T5's on my tank for 23 months now, just wondering how long most people change out their lights.

 

[sjkarrow87]

8 to 9 months i change mine out...

 

[davocean]

9 months for me, a year is really pushing it.

 

[Paaxil]

Yea, I thought so. Starting to get some diatoms, figured it was due to lighting.