Ramp up halide photoperiod?

[Steve175]

For a variety of reasons [not the point of the theead please ] I have decided to switch back from LEDs to a T5/Halide mixture over my SPS dominated reef. My display tanks are deep, so I have always run 400W halides. I have set it up with Radium 20K mogul bulbs (Giesemann fixtures). I have 4 T5 bulbs as well: currently running old actinics. My LEDs were running with a peak of 80% blue and 30% white. My main question: how long and rapidly should I introduce the halide photoperiod. I am thinking of going pretty slowly with only an hour of halides a day for a week and then add an hour each week until I get to 8h. However, I would love the advice of some SPS gurus on what they would do over their reef in this situation. Also, it has been a while since I ran T5: what bulbs should I run? Thanks in advance, Steve

 

[Piper27]

I would start with 3 hours and ramp up an hour every 3 days or so. Use egg crate to block the light so it's not as powerful. This is what matters most. The intensity is what y ok u need to acclimate not the length of the burn time. I normally stack two egg crate together and remove them according to how well things adjust. Got any pics of the tank?

 

[Ostentum]

Once you ramp up all the way I wouldnt go over 6.5hrs at the max. You can easy get to photo inhibition, which causes the corals to shut down, with acros over 6.5hrs. There have been some good studies done on this I believe Dana Riddle even did one a couple years back.

 

[Piper27]

Shut down? How's that work? The corals on the reef dont shut down? Post a link if you have one.

 

[Steve175]

Once you ramp up all the way I wouldnt go over 6.5hrs at the max. You can easy get to photo inhibition, which causes the corals to shut down, with acros over 6.5hrs. There have been some good studies done on this I believe Dana Riddle even did one a couple years back.

Interested. This is the first I have heard of this as well. Please elucidate.

 

[jda]

It is something that Dana Riddle has written about using Porites. It is a good start, but there is still way too much real life experience that contradicts what he is saying, especially with Acropora. There are all kinds of control issues and assumptions that are made between different types of "coral." You can search for his many articles - Google knows how to find them. He lays out his tests and the equipment that he uses and you can make your own assumptions. All that I know is that I grew Porites in a fuge under a 60w incandescent bulb, so they are not all that demanding.

I run my Halides for 11 hours, on and off with a light timer. I have 250w HQI, so about the same output as a 400W Radium. The 11 hours gives me more growth and color than 8 hours... all that I need to know.