help with metal halide

[markdt]

any one use a flat relecctor with bent edges or does every one use the spider reflector, for metal halides Also look at the below link and let me know if this would work or would it be better to get a spider reflector.

http://cgi.ebay.com/Dual-250-Metal-Halide-48-Reef-Aquarium-Retro_W0QQitemZ7738997460QQcategoryZ46314QQrdZ1QQcmdZViewItem

[clown2be]

That would work just fine, I used the same thing for years.

[coralfarmer84]

Looks fine to me. You could always change the reflector later in life if you don't like it

[j0tca]

I use that type of relfector and have always liked it. I've never even thought of changing.

[d4a2n0k]

I posted in your other thread but just wanted to say I respectfully disagree with the above. If you are keeping low light corals they are fine but then you are just wasting energy. Proper reflectors are not just only for T-5's. You dont have to spend a fortune on Lumenarcs but even Spider Light relectors will be noticeably brighter than the flat reflectors. The flat reflectors waste the majority of the light out the sides instead of in the tank where you want it. They are very inefficent.

[j0tca]

Hmm,

Not to disagree with d4a2nok to strongly here but let's digress into some point source illumination physics for moment or two.

Light illumination is very simple and intuitive, the intensity drops exponentially away from the point source (in MH cases the light inside the bulb). Think of a sphere of light around the point source. All equal areas of that sphere will have equal light intensities through them. 1” away from the source, lets call the full intensity 4pi representing the area of a sphere of radius 1. 1” sq area of this has an intensity 1/(4pi), or an intensity of 1, 2” away from the source has an intensity of 2/(4pi(2^2)) or 1/4. On our fixtures, the sides are about 12”-16” away, compared to the front and back being 3”- 4” away. If you were losing 1/16th of the light out of the front and back, you would be losing 1/144th or the light in the same area out of the sides. In a standard setup the reflector sits above the bulb and curves down beside it. The greatest loses in light come from the gaps in reflecting material the closest to the bulb. This is the area closest to the bulb with no reflector around it, i.e. the space directly in front and behind the bulb. This gap is also the same for most types of reflectors.
So, except for a pendant, the difference in light lost in the reflectors is not that great. In fact, cleaning your reflector frequently makes an infinitely greater difference than the type of reflector you are using (pendants excepted).

[d4a2n0k]

Without getting too deep here as I am not a math wiz by any stretch. I feel if you open your canopy and get blinded with light, there is a lot of wasted light bouncing around inside your canopy. You are wasting energy and just not getting the most from your light. You are paying for 250w (or 175/400 depending), might as well get the most out of it.

DE reflectors and Lumenarcs are the best at pointing all the light towards your tank. They are 4 sided reflectors in which no light can go anywhere but down. The Lumenarcs let you position the bulb right in the center as to accomodate the different sized SE bulbs. Spider lights are open at 2 ends. I feel the flat reflectors give you no more reflective light than just painting the inside white and mounting the mogul base directly to the canopy. Flat reflectors just dont work well.

This site shows some spectral graphs of some reflectors including the Lumenarc and is a great article to read on reflectors. http://www.advancedaquarist.com/issues/mar2003/feature.htm

I recently went from a flat reflector to Spider Lights and finally bit the bullet and got the Lumenarc Minis a few weeks ago. It was hard to swallow the $125 price tag and not even getting a finished pendant until I turned the lights on. I was blown away from the intensity and spread out of these even over the Spider Lights. I used the same ballast and bulb so nothing else changed.

Sort of stealing from the article but always remember that half of the light to come out of a bulb goes upwards. You need to get that light towards the tank and there are more efficient ways than others.

[markdt]

I just wanted to say thanks for the advice and to let everyone know that the below link is want I bought.

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=7738990454&rd=1&sspagename=STRK%3AMEWN%3AIT&rd=1