What type of glass

[thatguy559]

Im curious as to what type of glass is used for DE halide fixtures. the reason for this question is that most of you know that i made the switch to plasma. I was not happy with the reflector that was supplied with the fixture so i retrofitted my plasma with a lumenarc reflector. i had the light running without a glass for about 8 hours and sun burnt my corals. so i went out and bought a piece of glass that has 95% uv blocking. i am noticing that my monti cap is dulling out in color and i believe its due to the new glass. corals get their bright colors from UV rays so if im blocking them then they will dull out.

water parameters:

ph- 8.2
nitrate-0
ammonia-0
cal-550
alk-9 dkh

 

[Krish]

I did a google search on what type of glass is used for DE halide bulbs and an article I read said they use UV filtering glass. I then googled "Types of UV filtering glass" and a whole bunch of different types popped up. Here's the first page if you want to browse Google . Apart from that, sorry to hear about your corals. Hope they bounce back.

 

[thatguy559]

thanks krish for the links i was lost in google as well

 

[Krish]

Haha!! Hope you find what you need!! This is where I got that info of UV filtering glass from.

best lighting fixtures and bulbs at cheap prices

 

[CRASHFIREJOE]

UV shielding

I use regular glass from my local glass shop 3/16 inch then add a laminated uv shield to it. It is the stuff you can get from Lowes and laminate onto to your home windows as a uv blocker like a car tent but it is clear and works well.

 

[thatguy559]

does the glass itself have any uv blocking ablities? like if i went with a 1/4" thick glass?

 

[CRASHFIREJOE]

I am no expert but have read and some say it does especially if you use "green" glass it is clear glass but when you look at it from the cut side it looks green. I used 3/16 green glass and still was bleaching my SPS due to high UV that is why I laminated the uv shield and everything colored up nicely after.

 

[thatguy559]

okay what percent its that uv protection sheet

 

[ac7av]

Ill bet if you call the local glass shop in town and tell them what you need they could probably get it in the size you need. There may not be a specific name for it to go over a light but any 100% uv blockage clear glass will probably do the trick.

 

[eww]

If you buy laminated clear glass (the type with a plastic sheet sandwiched between two thin pieces of glass) it will filter out 99.9% of UV rays. The only concern my be in heat build up in the glass. I don't know what that might do to the plastic laminate layer. It may or may not cloud over time.

 

[thatguy559]

i dont want 100% block....i went to the local glass shop here and got 97% after extensive readings not all of the mh fixtures or SE bulbs block 100% the reason for the bright colors are because of uv. the ocean filters out a lot of the rays but there are still a lot that make it down to the corals which gives you the colors in the corals. i just want to block 360nm and down.

 

[user 2204]

What you're looking for is a glass tha twill block out the UV-B and UV-C rays but allow for most of the UV-A rays in.

I'm not sure but I think you might have been the one who advised me to check into picture frame glass. As I had a forum asking the question as to what the best glass would be for a DE bulb.
http://www.reeffrontiers.com/forums/f14/need-help-glass-uv-radiation-protection-59648/

Here's a good write up on Wiki about UV.
Ultraviolet - Wikipedia, the free encyclopedia

For those who do not wish to read, summary is the following in regards to UV and what actually comes through the atmosphere,
"The sun emits ultraviolet radiation in the UVA, UVB, and UVC bands. The Earth's ozone layer blocks 97-99% of this UV radiation from penetrating through the atmosphere. Of the ultraviolet radiation that reaches the Earth's surface, 98.7% is UVA."

Someone did mention a good idea for laminate glass (aka Safety Glass), such as the automotive manufactures do with windshieds to block out UV. In any case I would recommend making sure to get tempered glass, as tempered glass can withstand more heat than that of regular glass.

 

[user 2204]

The amount of UV which gets in will vary depending on the type and treatments of the glass and the thickness of the glass. Almost all glass (certainly all commercial glasses) absorbs some UV light.

The reason for this absorption has to due with the bonding of each glass type. Most commercial glasses are sodium-silicates. These glasses consist of a connected silica network, which is broken up by an alkali (sodium). The addition of sodium breaks the network creating non-bridging oxygens, which lowers the melting temperature as well as reducing the energy of electromagnetic radiation needed for absorption. In combination with small amounts of iron impuriity, which leads to intense UV absorption bands, these non-bridging oxygens prevent the transmission of UV light.

It should be noted that different glasses have different UV edges (the frequency of UV light that begins being absorbed). Borosilicate glass with small amounts of alkali will actually transmit further into the UV spectrum as a result of the boron anomoly, with fused silica (pure SiO2) glass transmitting the furthest. Even fused silica though will only transmit into the very low energy UV light.

In essence, the more loosely the electrons are bound, usually because they are not involved in covalent bonding in the case of non-bridging oxygens, the less UV light is transmitted.

The process of photochromitism utilizes this effect where charge transfer bands from added transition metals cause glass to change color when exposed to UV light. This is the result of electron transitions within the glass to more excited states. When the glass is no longer exposed to UV light the electrons return to their equilibrium position and the glass clears.

Most tempered glass, i.e. door glasses, back glasses, quarter glass...is UV glass.
Quartz will pass most UV.

 

[user 2204]

And finally here is another good source for UV info.
The Skin Cancer Foundation - Understanding UVA and UVB | UV Information

They do mention that "UVA penetrates glass, consider adding flat, tinted UV-protective film to your car’s side and rear windows as well as to house and business windows. This film blocks up to 99.9 percent of UV radiation and lets in up to 80 percent of visible light."

But on the otherhand, they do not mention that UVB or UVC penetrating glass. So theoretically standard/tempered glass should block out almost all the UVB and UVC harmful rays, while allowing the UVA rays to keep the corals happy and full of color.

 

[thatguy559]

sweet thanks just what i needed, my plasma doesnt put out that much heat i can touch the glass after its been on all day