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JW3571
12/09/2010, 02:23 PM
So I when i upgraded to a 90g from a 46g i got new lights. two 250 mg with 4 t5ho. I guess it's been a little too much for my corals, a lot of them are starting to bleach. My question is how do re-start the acclimating to the light? Do I keep all the lights off for a few days or just the mh off. Then start turning the mh on for a 30 minutes and then add 30 minutes every other day? Will this work? How do I get their color back?

Palting
12/09/2010, 02:44 PM
I made a small wooden frame, 20"x8", and attached 4 layers of screen and placed it on top of the tankm for a green stylo that was bleaching. It is working, and I plan to remove a layer a week until I can take the screen off completely.

Applying the same principle for your case, you can probably just lay 4 layers across the top of the tank, and start taking a layer off each week when the coral start to recover. HTH!

Toddrtrex
12/09/2010, 02:57 PM
Leave your photo-period as is -- just use layers of window screening. I prefer 3 layers, with removing a layer every 5-7 days.

http://i5.photobucket.com/albums/y189/toddrtrex/33/Lightacc6.jpg

JW3571
12/09/2010, 08:24 PM
Does it matter how long i keep the actinincs on? Also, I don't have the netting and the top to set it on. Can't I just start with the mh on for a short period of time and then move up from there?

Toddrtrex
12/09/2010, 08:47 PM
You could, but I have found that using window screening (( can be picked up at any hardware store -- assuming that you are in US/Canada )), to be much more effective and easier.

BurN
12/09/2010, 08:59 PM
toddrtrex nailed it.

edsreef
12/10/2010, 12:15 AM
Does it matter how long i keep the actinincs on? Also, I don't have the netting and the top to set it on. Can't I just start with the mh on for a short period of time and then move up from there?

That's the way I've always done it.

greenbean36191
12/10/2010, 07:57 AM
You're trying to acclimate the corals to increased intensity, which has nothing to do with the duration of the photoperiod. The damage that causes bleaching is due to excessive intensity, so reducing the photoperiod does nothing to prevent that damage. All it does is allow less damage to occur before the lights go out. To prevent the damage from occurring in the first place you have to reduce the intensity, either by blocking some of the light, as with Todd's method, or by increasing the distance from the light to the coral. Reducing the photoperiod is not equivalent.

Now that your corals are already bleached, the best way to help them recover is to give them less light, more flow, and more food.

d3rryc
12/10/2010, 09:06 AM
I did some playing around with a light meter and some common screening materials when I replaced my MHs a couple of months ago, and I was surprise by the results. Black window screening blocks a whopping 40% of light, which is still quite a shock to the corals when that last layer comes off. White egg crate blocks 15-40%, depending on the light's angle of incidence. Deer/bird netting blocks only 5%. I suspended layers of deer netting over the tank so that I could make the adjustments in smaller increments. In the future, I'll take a light reading before removing the old bulbs and another after installing the new ones. Caculating the percentage of light increase from the new bulbs will tell me how many layers of netting I need to reduce the new bulbs' intensity to match the old ones, and then we're back to peeling layers ever few days as posted above.

Palting
12/10/2010, 09:22 AM
I did some playing around with a light meter and some common screening materials when I replaced my MHs a couple of months ago, and I was surprise by the results. Black window screening blocks a whopping 40% of light, which is still quite a shock to the corals when that last layer comes off. White egg crate blocks 15-40%, depending on the light's angle of incidence. Deer/bird netting blocks only 5%. I suspended layers of deer netting over the tank so that I could make the adjustments in smaller increments. In the future, I'll take a light reading before removing the old bulbs and another after installing the new ones. Caculating the percentage of light increase from the new bulbs will tell me how many layers of netting I need to reduce the new bulbs' intensity to match the old ones, and then we're back to peeling layers ever few days as posted above.

Interesting!