Re: Glass for Tank Top

[Neal De Pape <neal_depape at yahoo_com>]

Rachel Sandage asked:

> . . .I'm tinking about building a new hood for my 
> 72  bowfront, and I will need new glass for it. Is >
there any particular type  which you'd recommend? 
> It will be sitting a few inches under 5 55W PCF 
> lights. Are there some kinds which withstand the 
> heat better? How about  transparency? Does anybody >
make glass with anti-reflective coatings?

And Scott H. wrote a very thorough and informative
description of different types of glass and coatings. 
The only statement that Scott made that I would call
into question is this one:

> You can get ordinary glass.  It will hold up even 
> with the lights lying right on it...

It is true that the heat from even PC bulbs will not
melt, distort or break normal glass.  However, what
might break it is PC bulbs right on the glass and then
a large splash of relatively much cooler water, say
from a large adult male rainbowfish devouring fruit
flies...  Don't ask me how I know ;)

Rachel's setup will apparently have the lights
suspended a few inches above the glass, so I would
think that she wouldn't have any issues even with
enthusiastic feeders splashing the glass.  

But in my setup, with the bulbs only a 1/8" above the
glass, normal glass didn't hold up.  But heat
resistant glass, such as Pyrex, has for almost a year
now and many splashes.  It was nearly 4x the price
though, $70 for my 54 corner instead of only $18.

Neal D.


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