who ever invented tempered glass is a real jerk..
- Thread starter Capt_Cully
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Capt_Cully
Active member
Kat years ago I had a mishap with a DE bulb so I did tons of research so here is what i know:
Double ended bulbs are made of Quartz and not glass so they need glass shield to block UV. any glass blocks 99.99% of UV there is no special UV glass. However regular glass ( not tempered) will result in heating up and cracking in contact with splash from the tank or rapid heating/cooling which tempered glass will withstand.
Single ended bulbs are encased in a glass "Bulb" which blocks UV and does not require a UV shield but may need one to protect it from cold water splash since its just glass and not tempered
T5, VHO, any incandescent unless specifically designed to let UV through, block UV with their own glass.
hope this helps
dont try to run that light without glass on it... it'll wipe out your tank in the matter of minutes.
P.S. thickness of the glass may change intensity.
Excellent explaination! Now I feel bad. Tempered Glass Guy (or Girl), my apologies.
dan10342
New member
+2 on all glass blocks UV. I think thicker glass blocks more UV. I think the glass is TEMPERED so the intense heat from the halide... and the chance that cool water will splash it, wont crack the glass
Cptn Spaulding
New member
glass in general is a strange material.. if theres a small amount of pressure or the slightest smack on a weak point the whole thing shatters.. hasnt happened to me with an aquarium buy its happened to me with a glass fish bowl as well as a drinking glass. the bowl i just picked up when it had water in it and it just fell apart, cutting my hand. the glass i knocked with my hand slightly and it shattered from the impact. the impact from the fall over would have been much harder than my hand hitting it, but it just crumbled through my hand. luckily i was uninjured that time.
but basically i feel your pain, and that definitely has to suck a lot.
but basically i feel your pain, and that definitely has to suck a lot.
RandyO
Active member
Just to let you guys know, that can happen with single ended halides as well. I've had it happen a couple times.
The large outer glass shell of single ended halides is made of UV protective glass. It's very rare, but if your bulb get's splashed while running and cracks in just the right place, the outer shell can break and fall into the water while the inside filament is still undamaged. If that happens, the UV light will bleach everything it hits. Even fish can be killed by this.
Every time it's happend to me, it's been a 400 watt halide.
magdelan
Fish?
And always remember folks, 60% of the time, it happens every time!
Mark... about the "throat punch"...I invented that, just to let you know
manderson21
New member
Wow that would suck mine is tempered I was reading that you can usually hit the front of it pretty hard but if you hit the edges slightly it doesnt take much.
Willistein
Active member
There is definitely different glass that absorbs different amounts of UV. All glass is NOT the same UV-wise. Some can transmit 50% of the UV, some can block 99.5% of it. I would make sure you know what the manufacturer used and get something exactly like it.
Willistein
Active member
This is 100% NOT TRUE. All glass does not block 99.99% of UV.
eugeneK
slacker
Good point, specially made glass such as fused quartz based glass( or actually crystal) and pure SiO2 silica glass would pass UV. These would be custom manufactured, expensive and almost impossible to find.
Ordinary commercial glass also know as Soda-Lime glass blocks almost all light under 400nm(UV) and what is used to make tempered glass for MH lights.
The reason UV glass cost more to manufacture is that the melting point of pure silica is over 2300 degrees and adding soda lowers it to 1500 and is more economical.
I am full of useless knowlege
"Ordinary window glass passes about 90% of the light above 350 nm, but blocks over 90% of the light below 300 nm." -Wiki, http://en.wikipedia.org/wiki/Ultraviolet#Blockers_and_absorbers
I am full of useless knowledge and interweb searching skillz
Ordinary commercial glass also know as Soda-Lime glass blocks almost all light under 400nm(UV) and what is used to make tempered glass for MH lights.
The reason UV glass cost more to manufacture is that the melting point of pure silica is over 2300 degrees and adding soda lowers it to 1500 and is more economical.
I am full of useless knowlege
"Ordinary window glass passes about 90% of the light above 350 nm, but blocks over 90% of the light below 300 nm." -Wiki, http://en.wikipedia.org/wiki/Ultraviolet#Blockers_and_absorbers
I am full of useless knowledge and interweb searching skillz
Willistein
Active member
from 320nm to 400nm it does not do very well (UVA). Not sure how bad this is for corals. It's also a function of the thickness. In UVB range (280-320nm), which is more damaging to corals, it does very well.
sg1838
New member
I'm sure with the Rochester optics community, there has to be a URS member that is VERY knowledgeable about the transmissive properties of various grades of "glass". Any U of R optics grads out there? How about COM/LLE staff members? Tropel / Melles Griot alum (which I am a part of)?
Capt_Cully
Active member
Talked to Sunlight supply, manufacturer of the Maristar fixture and they assured me it is just plain old tempered glass without and special UV protectant. I must say I feel a little leary about it, but this is what the manufacturer recommended. So I ordered a piece to be cut from a local glass store....for $37 I might add. Wish me luck.
Willistein
Active member
I asked my optics engineer coworker, she wasn't sure. I'm on the mechanical side, so I'm not qualified I'm sure you'll be fine with what the manufacturer recommended.
I'm sure you'll be fine with what the manufacturer recommended.
Capt_Cully
Active member
OK, new ballast in.
I have slid the remaining glass pane over the exposed halide. I am just running T5's right now. Tank has been dark on the right hand 2/3rds. But, in a day or so, do you think it'd be ok to run the exposed halide because it's over the glass center brace. I seriously doubt it is tempered.
I have slid the remaining glass pane over the exposed halide. I am just running T5's right now. Tank has been dark on the right hand 2/3rds. But, in a day or so, do you think it'd be ok to run the exposed halide because it's over the glass center brace. I seriously doubt it is tempered.
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