New Metal Halide from PC adjustment?

90g tank. I currently have 360 watts of total light. I am changing to 2 x 250 watt Halide with 2 x 54 watt T5.
How can I adjust my corals to the new light?
A friend told me to put window screen over it in 5 layers and peel a layer off every couple of days (I have rolls of this now).
Another said egg crate (would need to buy)?
Any suggestions.
Just have couple Hammers, Frogspawns, mushrooms, GSP, Torch, etc..

thanks!

John

 

When I upgraded to T5s from PCs I initially didn't cut back the photo period enough and put a burn on a toadstool. So I cut the full lighting back to 4 hours a day and then added 1 hour per day.

 

Did that hurt your corals at all? Such little light? Did you keep your acintics going?

 

It actually probably wasn't less light. I'm just thinking here, if your photo period is 8hours you've got 8x360 = 2880. You're going to 500 total watts, so I'd think if you did "500x = 2880, you'd get your exact photoperiod for the first day or two. About 5 hours and 45 mins. That's all if I'm correct, but I could be totally wrong. Let me know how it turns out.

 

I think I am going to do 5 hours a day for MH and then run the Ac for 10.

thanks!

 

The screen method works well, but I would use 3 layers and not 5.