When bulbs age, they lose their brightness, (called PAR) and their spectrum of color shifts. No matter how good your eyes are, you can’t see these changes.
So when you put in fresh bulbs, the new bulbs have more PAR and a different spectrum of colors.
Therefore, the MOST important thing you can do after you change your bulbs is to slowly ramp up your photo period (how long your lights are on in a day).
The first day after you change your bulbs, only leave them on for 2 hours, then every 4-5 days, add an hour, slowly building back up to your full photo period. If you see corals bleaching, or turning brown, slow down! Back off one hour and leave your lights there for a week, then add in an hour and see how your tank reacts.
(For you tank dabblers, I’ve seen fish hide all day when new bulbs are installed, so ramp up your photoperiod as well, but you can add 2 hours each day)
Why do corals react this way?
It is the reason that when you go to the beach for the first time in the summer, you burn. Your skin is not used to the bright sun, so unless you put on sunscreen, your skin burns. When you put in new bulbs that have a higher PAR rating, and a different color spectrum, your corals can’t handle the sudden exposure to this new light and they “burn” by bleaching, or turning brown.
For light bulbs in your tank, change them every 6 months, and then slowly ramp up your photo period.
{ 4 comments… read them below or add one }
If I could understand is something like this:
Photoperiod from T5 white 8:00 to 7:00 ant T5 Blue 9:00 to 8:00
So you are suggesting that when new bulbs are inserted that the photoperiod becomes slower like this:
1st week 8:00 to 6:00 white 9:00 to 7:00 blue
2nd week 8:00 to 7:00 white 9:00 to 8:00 blue
Something like that
Luis…Here’s how I’d ramp up your lights:
day 1-3: white’s on for 2 hrs, blues on for 4
day 4-7: whites on for 4 hrs, blues on for 6
day 8-11: whites on for 6 hrs, blues on for 8, etc, etc
Hi Mark,
In my 52 gal marine aquarium i have a 192 Watts power compact lighting system (96 Watts Daylight and 96Watts actinic). Could you tell me what must be the light photoperiod? How many hours Daylight and How many hours actinics?
Thanks
Eduardo…its really up to you. I run my actinics for 12 hrs and my halides for 7 hrs.