Heat safe glass for DIY pendant

[george1098]

Hi guys
so I want to upgrade my light pendant to a 2x250W MH which i will make myself. I want to put a pain of glass to protect the light from water splatter and the aquarium from the posibility of a bursting light. My question is, can i just use a regular thin pain of glass? or do i need to get something special to be able to take the heat of two big MH lamps?

thanks dudes

[RichConley]

SE or DE?

[george1098]

SE

[Russ Braaten]

Tempered may work but there are special glasses that work well with heat, like those on halogen lamps and coffee pots. Regular glass will break.

[george1098]

yes, thats why i ask as i was looking at my halogen lamp with the special glass. it feels almost plasticy.

[mikeadams1985]

ring up your local glass dealer and ask them ?
sure they would know better

[george1098]

that was plan B incase the reefers didn't know ;) I may also call up a halogen light manufacturer and ask them what they use

[RichConley]

How close to the bulb we talking? The glass on most DE pendants is just tempered plate glass.

[george1098]

well average i would say, no less than an inch and a half away from the bulb
the reflecter i'm using now which i made myself is protected by 1/4" acrylic, and the bulb is about 2 1/2" away from the bulb. it is warped a little bit from the heat but has heald up pretty well.

[TroyPierce]

I have a double 175W (SE) Hamilton unit that has a plexi sheet (looks like 1/4 inch acrylic) instead of glass. There's a fan in each end (one in, one out) and the plastic stays nice and cool.

When I built a small, single, 175W (SE) light for my sump, I used standard 1/8 inch acrylic. Again, I have two fans on the light abut it never gets hot enough to soften the acrylic.

An acrylic sheet will also allow more light to pass through than glass will. Not to mention, if it DOES get too hot, you won't have shattered pieces of glass to fish out of your tank.

[george1098]

i could probably re-use the acrylic sheet i have as my pendand now, i was just worried the 250's would burn much hotter than the 175. i have 4 fans with cool LED's i plan to install, so that should hopefully keep things nice and cool

[god910]

Okay, I'm going to be retarded for a minute here and ask this, I read it somewhere, maybe someone trying to sell me snake oil, but I remember hearing that glass and even "un-treated" Acrylic will reflect a good majority of UV that our reefs need. Could someone shed a bit of light on this (no pun intended) and if it's B.S. or not? Thanks.

[TroyPierce]

Sounds like Balogna Saurkraut to me. Most manufactured unit's I've seen have a plastic sheet between the water an the bulb. My Hamilton unit specificaly says it serves two purposes: Protect the bulb from spashes and filter out UV that is harmful to our tanks.

[george1098]

technically it would block a bit of the light radiation that you do want, but its an easy compromise as it will keep your reef safe from UV's and glass shards and other contaminents if a bulb breaks

[dpieroni]

I am using since 1 year ago a sheet of galss with my 250w DE and have no problems.
First I use a 6mm glass and broke, then I put a 3mm sheet and works ok.
When the sheet is thin, the glass heat quickly and it doesñt broke.
take in mind that my glass is 6 in fro the bulb.

[kellymm7149]

SE bulbs don't need a glass shield as they already have one. that is what the large outer glass, Also called an envelope is for. DE bulbs on the other hand don't have one that's why they are so much smaller and they need a shield to protect your tank from too much UV, if you shield your SE bulbs you will be blocking out a lot of their beneficial UV light unless you use a piece of optically clear glass such as starfire. If you look at a piece of regular glass from the side you will see a green tint the green tint you see is iron and lead and that will filter out the UV