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FAQs about Canopies, Tops and Housings for Lighting for Marine Systems: Reflectors

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Reflectors; gauging their effectiveness        5/14/15
Hey Bob.
On my scrubber I have 5 inch metal reflectors from depot. A lot of light is escaping peripherally, so my dad went to home depot and got me 8.5 inch clamp on work lights instead.
They are a carbon material, so they won't rust. The insides are white (reflector portion), as opposed to metallic aluminum color. Will white reflect well, or do you need the shiny chrome looking stuff?
<Test them out w/ your meter.... and keep reading furiously>
Re: Reflectors      5/15/15

Hey Bob,
I ran both reflectors, with same bulbs side by side, and the par difference was minimal 4 inches directly in front of bulb.
As expected, the bigger, 8.5 inch white reflector had better values off to the sides then did the 4 inch metal reflector.
Directly in front by 4 inches gave me about 220 par, off to sides around 180 on the questionable white one.
From that I will use the white ones, and my next test will be in the pudding (or algae).

DIY Reflector Hell gentlemen! Thank you for your help and for this website which is a wealth of information. My question is regarding Power compact bulb reflectors. Because my half hexagon has a custom light hood I have considered purchasing some bulbs that advertise a built in 180 degree reflector. I realized that on some bulbs this 180 degree reflector is nothing more than a silver heat resistant sticker or some kind of white paint on half of the bulb which allows it to reflect light. I happen to have some white spray paint at home that is made for BBQ's. It is heat resistant and can stand up to the heat generated by any fluorescent bulb. I thought about using masking tape and a little creativity to spray the back half of the bulb with this white paint. <Interesting> I figure it will perform just like these other bulbs that advertise a built in 180 degree reflector. Of course I would let the paint dry before actually using it in the fixture. My hope is to increase the amount of light that is reflected down into the aquarium. I know it would probably be better to just buy reflectors but money being tight I just thought this might help a bit. What do you think? <Worth experimenting... not all paints are much "light reflective" though. I would spray one, test it with a PAR meter... you can likely borrow the latter from a local LFS or reef/marine club...> Am I on to something or is the idea worthless. Can anyone out there maybe test this idea and use a light meter to see if it increases the amount of light reflected more than a polished aluminum reflector? <Oh yes... I would write Sanjay Joshi or Dana Riddle re this idea... Again, worth trying. Bob Fenner> Thanks, Mario.

DIY light hood  - 01/03/2006 Hi. <Hello. John here with you this evening.> I'm planning to build a hood with 2 250W MH and 2 96W PC bulbs. My question is, what type of reflector is best? <For the halides or PCs? For the halides, the shape of the reflector is critical - there are a number of variables. Do check out Sanjay Joshi's interesting work on this subject- the most relevant of which is here: http://www.advancedaquarist.com/issues/july2003/feature.htm . Bear in mind that all double-ended bulbs must have a piece of protective glass installed below the bulb to block damaging UV radiation - it may be easier / safer to purchase a fixture.> I have read that some people  paint the inside all white, some black <Surely not black!.> Others use a mirror type  reflector and some polished aluminum. thanks for your advice. <You're welcome! Best regards, John.>

Finding A Suitable MH Reflector - 04/11/06 It has been quite some time since I had to go to the all knowing WWM Crew with a question, but since this is a continual learning hobby, I have returned! <<Indeed it is...for me as well...welcome back>> I am rebuilding my 65g reef tank due to a forced relocation.  I have 4x 96w VHOs and 2x 250w MHs.  It isn't hard to fit all the lights in the canopy (19"x37"), but I had to seriously mangle the reflectors to put them in the first time. <<I'll bet>> Basically the MH's parabolic reflector had to be partially bent closed from their ~13" width to about 8" and I had to cut the VHOs' reflector in half to about 5" each because I have 2x VHOs on either side of the centered MHs. <<Not so much an issue with the VHOs, but this would seriously affect your "spread" on the metal halides>> I want to put a "less mangled" reflector in the hood this time. What do you think about a simple 36"x18"x2" reflector instead of the mix-match I have now? Do you know where I can get such a reflector? <<Indeed I do!  PFO has a 36" parallel reflector with dual mogul sockets and "shelf" to mount your VHOs.  I have two of these over my 8ft tank.  Check out an example here:  http://oceanencounter.com/Merchant2/merchant.mvc?Screen=PROD&Store_Code=OE&Product_Code=P3PRW2MS&Category_Code=RSC  ...if you have any questions about the reflector, call Vince at Ocean Encounter...a very helpful individual>> Thanks (again) for the help! -Jeff <<Always a pleasure, EricR>> Best/Better Reflectors for reef light canopies Sorry, I was out of town for last few days. <Sanjay... no worries. Thank you my friend for taking the time to share your opinion> Of the pre-made reflectors, the 2 most popular are the spider light and the PFO reflectors. If you have problems with getting them into a hood, the next best option is to make your own by buying sheets of the reflective material and installing them in your hood. Champion (Lighting and Supply Company) sells different sizes and there may be others on the web who do as well. White paint is not a good solution, neither is the flashing from Home Depot. The reflective material should be anodized to prevent corrosion. Using these reflective materials (most of them are the Everbrite by Alcoa) you can easily get 20-40% more light into your tank. Sanjay. <wonderful... I'll be sure to pass this along. Thanks again very kindly, Anthony Calfo> Lighting and Reflectors Anthony- Thank you so much for the email from Sanjay! I feel quite honored to have both of your input into my lighting system. :)  <it is my honour that anyone should care to know my opinion> I just ordered my 2x175 watt MH PFO dual, & 110 watt VHO actinic IcaCap430. The MH are Ushio 10K and the Actinic lights are 03 URI (or IUR, RUI, IRU.. damn my dyslexic mind!) <correct...URI, outstanding quality fluorescents> I ordered the spider reflectors. My original question was not if the Spider reflector was my best choice, but if I can use the Spider Reflector with the VHO bulbs below it.  <I do recall... my apologies... I did not have enough experience to comment and Sanjay may have overlooked it> No worries, in 5-7 working days I will find out if it can work. In any event I know now what will be my best second choice if it does fail to work. <please do let us learn from your experience> Thanks for your time and effort! It has made difference for the positive for my future coral. Robert <you made the difference for caring... continue to do so. Anthony>

Jumping Fish, Tank Cover, Reflector Hello there, I decided to remove the eggcrate grill covering my 55g tank's top. I noticed that the PC lighting made a cool looking shimmering effect. I also noticed that the white eggcrate reflected a lot of the light away from the water. <Eggcrates have a top and bottom. Take a close look and you will notice that the sides of each square have a bevel to them. You want to orient it so that the bevel works to focus your light.> Should I keep the eggcrate on? <I like them.> I'd like to leave it off, unless that shimmering effect is unhealthy for the fish and anemones <No, just fine for the animals.> (3 FL Condys, and a bubble tip...I'll be getting rid of the Condys in time). I have a yellow tang, Kole tang, cinnamon clown, 4 damsels (4striped, 3 striped, and two yellow tails). Are any of these known jumpers? <Anyone can jump.> I currently have 2x55w PCs (two more on the way) hanging off the inside top of my oak canopy...I drilled the clips that hold the bulb into the canopy and snapped the bulbs into place, then took some metal-like yarn and tied the ends of each clip together....just in case the bulbs slipped out of the clips, the wire would catch it...I don't know if this will actually work, but it gives me peace of mind since they are now just hanging over open water (3.5 to 4 inches over the water...hard to get an accurate measurement). I am saving up for reflectors, but right now I have aluminum foil reflecting the light back to tank. Is this OK/safe to do for the meantime? <Sure, have seen it done many times.> I came across a FAQ in the archive and Bob mentioned to someone something about using Mylar or Mylar sheets or wardrobe mirrors or something like that for "something", but that "something" was never stated in the question (it was a reply). Was Bob suggesting using this reflective material as a light reflector? <Yes> Could I use pieces of cut mirror as reflectors? <Yes, but rather heavy.> Oh, I realized the other day that my 55g tank is not really a 55g tank. If I use the dimensions/measurements of the outside of the tank, and divide by 231, I get 55 gallons. But when I measure the inside of the tank, it actually comes out to about 40 something gallons. Do tank manufacturers label their products based on inside the tank measurements or outside the tank measurements? <Outside measurements.> And last, do I use the manufacturer's "55g" label when considering lighting needs (e.g., 4 watts per gallon for 55g tank equals 220watts) or my own calculations of actual in tank capacity? <The manufacturer's labeling.> Very last, does this make a difference in calculating for live rock stocking? <No, everyone uses the manufacturer's labeling for convention.> Thank you again, Randy M. Yniguez, MA <You are welcome. -Steven Pro>

Re: Advice Please Lighting (canopy reflectorizing) Sounds good but surely mirrors have more reflective properties than any other material and if I seal the mirrors well on the inside of my tank it shouldn't cause harm ??? Just asking you are the guru please advise . <Mmm, will have to look for a while in analog files... folks have tested these materials for reflectance properties... and the "mirrored closet" material (Mylar encased) comes out near tops... and is relatively cheap, easy to work with... Glass mirror and silvering can rust, chip... Bob Fenner> Werner Schoeman

Re: Advice Please Lighting Hi Anthony thanks I have read the link , quick question apparently mirrors aren't the best bet but due to rather big financial constraints what about using normal aluminium foil in my canopy ?? <Pardon my intervention. Bob F here. I am a big fan of the Mylar and acrylic (inexpensive and good reflection properties) that you can buy through plastic fabricators, large hardware stores... and cut to size, install with silicone sealant.> Werner Schoeman

Reflector question Hi Arthur> OK, for the 75 gallon tall reef tank, I think I've finally decided to try swapping my 2 250W 10K MH for 2 250W 20K Radiums. It's not a drop in wattage, but I wanted to at least try it before tossing the ballasts and having to get new 175W ballasts, and I can get a pair of Radiums for around $160. Can I maybe drop the wattage going into the tank by removing the reflectors?  <The Radiums sound cool Not quite the same as 400watt Radiums, but should be nice! No, you won't lower the wattage of anything, that's the amount of power the lights use (250 watts), not the amount of light they emit. Removing the reflector WILL reduce the amount of reflected light, but it won't do anything about wattage, and MAY be a fire hazard without it.>  I have Spider reflectors, and removing them should help in lowering the overall wattage entering the tank, no? I'm a little concerned about warping the wood of the canopy without reflectors - would you remove them or find some way of dampening them, maybe with heat-resistant paint for example? <No. Leave the reflectors and raise the hood or lights or use shading of some kind if you are worried about temporary added light levels. The Radiums should be about the same intensity but a different spectrum than the 10K's. Leave the reflectors, they reflect a LOT of heat from the wood hood and paint is painted onto....wood, that's still flammable!>  Thanks for all of the help the last couple of days...you provide an invaluable, extremely helpful resource for the reef tank owner to be able to ask questions that aren't covered by a FAQ... Arthur <Hope this helps you Arthur, Craig>

Plexi-mirrors Hi Crew! I'm planning to put 2 175W metal halides above my 80 gal reef tank. Future inhabitants: T. maximas, fish, corals (I don't know which ones yet) and some invertebrates. Enough light? I am planning to supplement with 2 110W actinic VHOs in the future, also (far future... no rush=no funds). Well here is my real question: I've been reading up on your canopy FAQs and Bob has suggested using acrylic coated Mylar or Plexi mirror as a DIY reflector. I am concerned that my metal halides will melt this material. Won't they? <Maybe> Will stand-offs for mounting the halides away from the mirror help? <Should. Do see the manufacturer of your light fixture's recommendations for how far they need to be away from acrylic> I love your site. It's full of a wealth of information and a friendly & helpful community of reefers. Thanks all! Iona <Thank you for writing. Bob Fenner>

Using mirrors in a canopy? Hi crew- I keep saying "this is my last question", so my apologies.  My canopy  is ready for the lighting to be installed.  Are mirrors better than  polished aluminum? << Hmmm, maybe.  Harder to bend and shape.  May be easier to clean.  Not sure what I would rather use. >> Mirrors are less expensive. << Really?  I bought the reflector for my 55 gal for $10. >> I know weight is an issue.  I do not plan on taking the canopy off,  except for emergencies, etc. Would the weight of thin mirrors ( 1/8") be too  much on the sides of a 90 gallon? << Weight is an issue.  Boy that is tough.  I think the main problem is getting a properly shaped set up with mirrors. >> Should I just go with polished  aluminum?  Stainless steel?  Mylar?? << Not Mylar. Also, not steel.  I would go polished aluminum, but I also like seeing people try new things.  So if you think you can make it go well with mirrors, then do so. >> Thank you so much. <<  Blundell  >>

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