metal halide lens

[mogurnda]

I only saw FlowerSeller's post about XM 10000K bulbs after mine were on the way from the group buy, but decided to try them anyway. The light looked great, but it only took about 15 minutes for one of my gorgonians to start bleaching at the tips. So, I'm back to the 8-month old Iwasakis for the moment. The gorg was fine within a day.

 

Looking at Sanjay Joshi's articles, I see that XM 10000Ks put out a lot more blue and UV than most other bulbs. So, I figure the problem could be:

a. The smaller blue peak in the Iwasaki left the corals unprepared for the more intense light. This could be remedied by using the "window screen method."

b. That UV hump is the problem, and I should add lenses under the lamps. Well, I should add lenses anyway for safety.

 

The questions are:

1. Does anyone know whether it's the intensity or the UV that is the problem?

2. No matter what, I'm installing lenses in the canopy. Would glass or polycarbonate be the better choice?

 

Thanks.

[Guest what up]

I use screen window about 3-4 layers to reduce the UV and aclimate the light to the corals and removed each layers in every 3-4 days. Good luck!

[mogurnda]

So nobody has an opinion on glass vs polycarbonate?

[Guest Keyoke]

I think both are fine, provided you take caution:

 

Poly has two major drawbacks that I can see.

 

#1 - It's supceptable to warping due to heat from the bulb... if there's plenty-o space btwn the bulb and the lense, you should be OK, just keep some air movement..

#2 - The UV emmited from the bulbs tend to break down the molecules holding the poly together. Thus resulting in a brittle, easilly cracked or yellowed plastic, tho it may not be bad enough to be noticiable for about a year or two.

 

As for glass.. the only problem is that it too is supceptable to heat. But in a different way than the poly. Glass won't melt, but if it gets hot, and then splashed with cool tank water it can shatter too.. tho admittedly, the glass has to be almost as hot as the bulb for this to happen.

[mogurnda]

I think both are fine, provided you take caution:

 

Poly has two major drawbacks that I can see.

 

#1 - It's supceptable to warping due to heat from the bulb... if there's plenty-o space btwn the bulb and the lense, you should be OK, just keep some air movement..

#2 - The UV emmited from the bulbs tend to break down the molecules holding the poly together. Thus resulting in a brittle, easilly cracked or yellowed plastic, tho it may not be bad enough to be noticiable for about a year or two.

 

As for glass.. the only problem is that it too is supceptable to heat. But in a different way than the poly. Glass won't melt, but if it gets hot, and then splashed with cool tank water it can shatter too.. tho admittedly, the glass has to be almost as hot as the bulb for this to happen.

31883[/snapback]

Yeah, I am leaning toward glass because of the sagging issue. Should be far enough away from the lamp so it won't get too hot.

[dchild]

Where will you get your UV-absorbent glass?

[mogurnda]

I was just going to use regular glass, which absorbs a good bit of UV.