How long should i have my light on

[Clownfishdude29]

I have zoanthids, green star polyp, and pulsing xenia in my 20 gallon. How long should i have the light on?

 

[lapin]

A good rule of thumb is as long as you have daylight outside, the tank should have light. Not full blast all the time. Ramp up then ramp down.
This can be adjusted so if its dark in the evening you can still light your tank, Just start the light cycle later in the AM.
Now if you at the poles ( Alaska ) this will not work.

 

[Ron Reefman]

As best as I understand it, most corals (really, their zooxanthellae, i.e. algae) only do photosynthesis during high intensity light, think 9 or 10 am until 3 or 4 pm out on a reef. So 5 to 7 hours of high intensity light is probably optimal. However, longer amounts of intense light are harmless... up to a point. The length of sunrise and sunset with lower intensity light is entirely up to you, the corals don't care.

I do a 4 hour very gradual sunrise, 6 hours of high PAR midday light and then 5 hours of a very gradual sunset. My last hour of sunrise and my first hour of sunset may also be strong enough for photosynthesis. So I have 6 to 8 hours of high PAR light.

 

[Biglew11]

I ramp leds up for 2.5 hours down 2.5 with about 9 hour at 50% then my t5 are on for 5 hours right in the middle of the time period.

 

[rwreef]

I do 12 hrs
3hr ramp up
6 hr peak
3 hr ramp down