When to replace your lights? Coralife

[dscount]

Okay this is a strange question. Not one I can seem to find a good answer about. How do you know they need to be changed?

I've a Coralife 260 watt light. Two Blue Actic and Two 10k White (All four are 65 Watt each)

When do you replace the bulbs? (Beside the obvious when they burn out)

Should you alternate and get one set done first or one side done first?

Both Whites first then Both Blue?
One of Each then wait and then the rest?

[tecwzrd]

Assuming you got the bulbs at the same time I'd replace all at the same time. Usually you should replace 7-10 months for PC and one year for MH depending on how long you leave them on each day.

If you go longer then that then as they reduce in brightness they also get bluer which usually leads to algae.

Without a PAR meter it's impossible to know exactly when they need replacing though.

[melosu58]

I have VHO lights and I change mine every 6 months. I change the 50/50 light first and then the super actinic a month later. It really depends on how much you use your light also. I run mine 12 hrs a day and someone who runs theirs 8 hrs a day should last a month longer if you get my example.

[dscount]

Thanks. I've always wondered about this. What is a PAR meter? Something I could find / borrow locally. Hate to spend the money, but it my tank is going to start looking ugly it's worth it to me.