lighting on/off
- Thread starter firedan
- Start date
Vinny Kreyling
Premium Member
Many split the day in half, I run 10 on 14 off with the sump the other way.
Ron Reefman
Active member
The zooxanthellae in the coral need close to midday light (9am to 3pm sun on a reef) for 6 to 8 hours in order to do all the photosynthesis they can. After that they shut down no matter how much light they get. But corals also use light to do other things than photosynthesis.
I do a 4 hour sunrise, 4 hour midday and 5 hour sunset. The last hour of sunrise and the first 2 hours of sunset are all still very intense enough for photosynthesis. The first 2 hours of sunrise and last 2 hours of sunset are really dawn and dusk levels of light.
I do a 4 hour sunrise, 4 hour midday and 5 hour sunset. The last hour of sunrise and the first 2 hours of sunset are all still very intense enough for photosynthesis. The first 2 hours of sunrise and last 2 hours of sunset are really dawn and dusk levels of light.
Flaring Afro
Puffer Geek
Only until 3? I thought reefs tended to have 12 hours of daylight. Hawaii gets 12-13.5 hours of daylight depending on the time of year. Granted that's sunrise to sunset which means some of that time isn't going to have light as intense as our reef lights.
Ron Reefman
Active member
The sun is up that long, but think about the angle on the sun in the morning and afternoon. Even the steep angle though a lot more air reduces the intensity, what do you think at lot more water does? Take a PAR reading just after dawn, at 8am, 10am and noon. You may be surprised how much the PAR changes and that's only due to the sunlight passing through extra air. Sunlight at 9am and at 3pm (not daylight savings time) is at 45 degrees from straight down. That means the light has to pass through almost 2 times as much air AND almost 2 times as much water to get down to the coral! I'd link a graph to show you, but photobucket is down for service (at 6:20pm on a Friday!!!).
zachxlutz
New member
faterikcartman
New member
I get the impression some may want to re-read this post. He's talking about six hours of "midday light". In other words, bright sun high in the sky. He doesn't run his lights for only six hours. He's got them on for 13 hours a day.
Hope this helps.
Ron Reefman
Active member
It's a simple graph. but you can see how much the energy falls off before 9am and after 3pm. I'll try to collect some PAR numbers during the day today and share them here.
Thank you for making that clear. Yes, I'm saying 6 to 8 hours of midday type lighting. Just like the reef, my tank is lit up for half the day (12 or 13 hours).
The zooxanthellae in your coral can't do photosynthesis when the light isn't bright (intense) enough. In fact, even when the light first gets bright enough, it takes roughly an hour for the zooxanthellae to do some internal chemistry work and get things running before it's actually making food. This photosynthesis process is a genetic thing which is a result of thousands of years of development where the coral only gets 6 to 8 hours of enough sunlight to do it's work. Running bright lights in our tanks for 12 hours or more doesn't change the way the process works. And just to be clear, running bright lights for 12 or 13 hours a day is not known to cause any harm either.
