Pendant lighting and water distance - How close can pendants be to water

W

waterbeing

Premium Member
[I'd like some thoughts and experiences from anyone using 250 to 400 Watt DE (or SE) pendants under a hood/tank top as it relates to potential glass breakage from water spash,etc. I've finished mounting 3 pendants under a hood for a new tank and the bottom edge of the pendant will be about 2 1/2 inches from the tank top edge (so about 4 inches from the water surface). I have no experience with the temperature of the glass in the pendant itself and when I set the top back on the tank to double check some clearances, I realized how close it was to the potential water line. While I know that it can in large part be changed with proper ventilation (which I intend to provide via tank top mounted fans pulling from the tank to the outside), I was wondering if I've just made a design that will HAVE to have it's glass tank top installed in order to prevent an accidental splash. I also know that a large splash won't happend too often, but just wondered how tempered/strong to thermal stress the glass might be and if anyone else has had any concerns/problems in this area (not that I have any choice at this point except to close the tank up by putting the glass top back on) :sosad:]
 
[Doug, you should raise your pendant up so that the glass and bulb are 9" off the water. You might even experiment with going higher as DE bulbs are more intense and as you raise them up the light coverage spreads wider.

I believe it was Mitch that posted about raising his lights to 14" off the water a few months ago??]
 
[My experience is that the glass would never get hot enough to cause breakage if it got splashed. I am assuming that yours gets around the same heat as mine, of course.

Four inches IMO is too close to the water to get your maximum light spread. I suggest aroujnd 8, or even more. That eliminates the splashing question too.:) Keeping the tops on your tank is a bad idea IME. You will have major heat issues, and it also prevents your fans from being of use if they can't blow across the water surface....... which compounds the problem.]



Edited By smiller on 1102855876
 
[10" from pendant glass to the water for me

DSC00002.JPG
alt="">]
 
[All,
Thanks for the input. I'm concerned about the various issues also, but unfortunately, I can't get them any higher without removing the top. Since we intend this to be viewed from 3 sides(1 side thru wall), I don't have the luxury of removing the top until I've tried just about every cooling alternative available, so I have to keep the hood on for now, besides wifey really likes it. :) I wish it were taller, but...alas it isn't. I plan on running 2-3 icecap fans in the top of the hood and possibly another 2 standard fans (read cheaper...) on the 1 side that is open. It may sound like a jet engine revving up by the time I get enought air moving in/out. :p. I'm hoping the shadows/lighting should be OK as there are 3 pendants (2 lengthwise-250W, 1 perpendicular-400W) and probably 2-60" VHO in a 6' tank (X30X24). If I ever get the 400W ballast I'm waiting on, I may try to do some temp tests before filling and cycling it too.. .. then we will have some idea of what we are facing before moving/consolidating other tanks. I'm sure it will be a real 'experience'. Additional thoughts/comments are appreciated.]



Edited By waterbeing on 1102880796
 
[Recently someone had a thread about cutting a hole in the canopy so the light would fit through the opening enough to avoid seeing the light. With some decorative trim you can hide the fixture itself.

Since you have two lights, it would be two holes.

The trim I saw in one thread was a nice looking baseboard that was mounted on the top, standing up 4" tall (just like you'd see along the base of your walls). The put a piece at each end and one across the front, mitering the corners. It would have been easier to show you the image, but I don't know where I saw it.]
 
[IMO you really should reconsider the direction you are planning to install your fans. Fans should be pushing air into the canopy NOT pulling air out. Couple of reasons for this:
1. Most fans are not meant to be exposed to air filled with salt. It corrodes them and shortens lifespan. Pushing fresh air into the canopy instead of pulling salty air out helps resolve this.
2. Positive pressure into the canopy usually results in better air movement than trying to "suck" air thru the canopy. (look at most computer case cooling and also I believe someone mentioned that the fire dept pushes air in to ventilate rather than sucking it out).

This has been debated somewhat in the past. Do a search for it and you will find several threads on it. HTH.]
 
[My lights were 14 inches off 6 months ago but since then I have moved them to about 10 inches off the surface. I can speak from experiance that water splashing on the glass shields will not break them. My cat decided to cannon ball into my tank. I was certain the glass shield was going to burst. The glass was so hot the water tured into steam almost instantly. Scared me to death but everythign was alright.]
 
You must log in or register to reply here.
Top