When should you change Light...

[carp31]

bulbs for reef tank? The local fish store told me once a year. My water levels are fine, but I am now getting some gooy red algae in my tank. Could bad bulbs cause this? My bulbs are over a year old. ANy help would be appreciated. Thank you.

 

[tizzo]

VHO's and PC are every 8 months max and halides are every year.

 

[carp31]

And if you dont does it cause red slime algae? I am going to change them out this Friday. thanks.

 

[tizzo]

Think ROY G BIV
For PC's and VHO's what happens is the white powder coating on the inside of the bulb (phosphers ?) starts to thin down thus letting more of the red/orange side of the light spectrum through. Corals use the blue green side and the grass on your front lawn uses the red/orange. So when you are emitting that color spectrum, pretty much anything plantlike will grow in it. Halides lose their intensity and emit the same results (more red light)
YOU can't see it but the stuff in your tank sure does.
Your cyano can come from a number of resources, but since you know your bulbs are old, that would be a good place to start.