Problems with new bulbs -- giesemann megachrome

[Ligershark]

my friend has a 265 gallon tank that is 30 inches tall and has 4 250w HQI bulbs and 6 80w actinic t5 lights that are 60 inches long. this tank was set up in early september. we recently changed from alternating coralife 10k, and 14k bulbs to giesemann 250 Watt 13000K MegaChrome Marine bulbs. Since changing my bulbs, we have had to move all the corals to the bottom half of the tank, where they receive less light and fare much better. these bulbs were about $100 each. he has since put his other lights back in the system and swapped out the megachrome and all is well. He has many australians, scroll corals, lps, softies....there is a lot in there especially considering the age of the tank. However all the water paramaters are good and all corals are doing well again. Does anyone have anything to say about these bulbs? I think they are farely new. I am trying to get him to go to the iwasakis, based on my own success with them but I am not sure if his corals can handle them since they couldn't handle the giesemann megachromes. any other recommendations for bulbs would be greatly appreciated. these are double ended 250w bulbs.

 

[Phyl]

Those bulbs must have an incredible PAR value (loosely translated to amount of useable light), or the old bulbs not much at all. Going from a low par bulb to a HIGH par value bulb can put the corals into light shock. Instead of instant transfer the corals would have been better served to be acclimated to the new lights through layers of screen or eggcrate covering the tank and removing a layer a week until the corals were used to the new intense lighting.

The same thing will happen by changing to any other high par value bulb.

Phoenix on PFO: 88
Geissman on Icecap: 63
Coralview on PFO: 54

I couldn't find a Coralife bulb, but you get the idea. The website with myriads of data can be found HERE

 

[RichT]

Does you friend have a lenses over the DE bulbs?

 

[sinkingbeach]

I love the giesemann megachrome bulbs, I use 2 14.5 K MEGACHROME coral 250 Watt - DE and a single Phoenix 14K for a bluer look over my tank. They produce a very crisp white light, my tank is predominantly SPS and they are thriving and colorful, most of my corals are less than 10 inches from the water's surface.

 

[MikeNapoli]

Tom,

I think it has to do with what phyl said. Your adding new bulbs which are going to be stronger. It could be the corals aren't used to the stronger light. What you should do is add layers of mesh screen over the top of the tank. Remove one every 4 days until you have your regular set up.

Also double check what Rich said about the UV glass covering the light.

 

[Ligershark]

first of all thanks to everyone for all the replies. Rich, there are glass lenses on the system under each halide bulb. im going to tell him to try the lense screening method. would the change of going from coralife to the megachrome bulbs vary that much if they were only 3 months old? thank you once again.
tommy

 

[Phyl]

Yes, if the PAR value of the new bulb (different for each type of bulb on each ballast) is greater than the par for the old bulb.

You could have a 250w bulb that has more par than some of the 400w bulbs or you could have a bulb that has less par than a 175w bulb. Depends on the brand, Kelvin rating, watts, etc.