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March 17th, 2009
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| | Fish Keeper
| Has anyone tried...
has anyone tried the reflectors you can put over the lights? im particular a 'Juwel 1200mm Reflector 36W', a website says they more than double the wattage outputted from the lamp, is this true?
Thanks
Jack | 
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March 17th, 2009
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| | Fish Keeper
| Yes I put one onto one of my tanks and it made and enormous difference.
i had to take some of the plant tha twere in the tank out as they were melting under the lights once it was fitted | |
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March 17th, 2009
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| | Fish Keeper
| cool, thanks jonah. should i only a single one as i have 2 floresent tubes and have 1.1 WPG already or should i go for a reflector for both and get the highest intensity i can? 
Jack | |
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March 17th, 2009
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| | Fish Keeper
| Quote:
Originally Posted by jack--sos  has anyone tried the reflectors you can put over the lights? im particular a 'Juwel 1200mm Reflector 36W', a website says they more than double the wattage outputted from the lamp, is this true? | Claiming that they double the wattage output by the lamp is a bit inaccurate. Having a reflector has absolutely no impact on how much wattage is produced, but a good reflector can increase the amount of light that gets into the tank.
And yes, I have use AHSupply reflectors over all four of my bulbs. | |
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March 17th, 2009
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| | Fish Keeper
| Mathas has you covered, and yes they may not double the wattage output but they do vastly increase the volume of light in the tank. Its not double as there is still leakage but it is significant
I had the same discussion witha rep at a trade show and pointed out nothing could increase the wattage and his answer was that if you had a 30watt tube and only half the light went into the tank then it was giving you 15watts to the tank. If you reflect the light from the back of the tube that normally goes out of the tank into the hood back down again then your available light increases from 15 watts up to 30watts.
Symantics and sales pitch but with more than a modicum of truth to it
Last edited by Jonah; March 17th, 2009 at 03:08 PM.
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March 17th, 2009
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| | Fish Addict
| i got it on my incandescent bulbs and it like doubles it beacause i have two 12 watts but it puts out 50w | |
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March 17th, 2009
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| | Fish Keeper
| wow Mathas, thanks, great link. i will get a couple when i next go the the trusty LFS (could be this weekend)
Jack | |
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March 17th, 2009
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| | Fish Keeper
| Quote:
Originally Posted by Jonah I had the same discussion witha rep at a trade show and pointed out nothing could increase the wattage and his answer was that if you had a 30watt tube and only half the light went into the tank then it was giving you 15watts to the tank. If you reflect the light from the back of the tube that normally goes out of the tank into the hood back down again then your available light increases from 15 watts up to 30watts. | While I would agree with what the rep was saying in theory, I would disagree with any assertion that the lamp is now producing double the wattage. As we're pointing out, there's a difference between how much light is produced by a bulb/fixture and how much actually gets into the tank.
Sticking something reflective over a 55W bulb does not magically make the bulb produce 110W of light. A good reflector might make a 55W bulb direct as much light into a tank as a poorly-reflected or non-reflected 110W bulb, but that doesn't mean 110W are produced simply by adding something shiny, it just means that a good portion of the light produced is normally wasted. | |
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March 29th, 2009
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| | Fish Keeper
| Hi and great thread. I am looking at the lighting situation myself. This raises the question that for low light plants for example, it is recommended 1.0 - 1.5 W min. are required per gallon. So does that mean that for a 20 gallon tank, if you install 20 watts of lighting, your plants are only possibly getting half that. So is the loss factored into the recommendation or should we double our lights or improve with reflection. ( this may be a topic for another thread, but is sort of connected ) | |
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March 29th, 2009
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| | Fish Keeper
| Quote:
Originally Posted by Lifesabeach This raises the question that for low light plants for example, it is recommended 1.0 - 1.5 W min. are required per gallon. So does that mean that for a 20 gallon tank, if you install 20 watts of lighting, your plants are only possibly getting half that. So is the loss factored into the recommendation or should we double our lights or improve with reflection. | You've found one of the reasons why the entire WPG concept is flawed. It's much like the oft-repeated "one inch of adult fish per gallon" suggestion for stocking fish... sort of helpful as a general guideline, but not exact by any means and not applicable to all situations.
For a low-light plant, you'd be fine without reflectors. They would likely help, but are not necessary.
If you want to increase the efficiency without spending the money on reflectors or trying to retrofit an existing fixture, painting the inside of your lighting fixture flat white is quite effective. A $3 can of spray paint supposedly gives quite good results. | |
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March 29th, 2009
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| | Fish Helper
| Quote:
Originally Posted by mathas You've found one of the reasons why the entire WPG concept is flawed. It's much like the oft-repeated "one inch of adult fish per gallon" suggestion for stocking fish... sort of helpful as a general guideline, but not exact by any means and not applicable to all situations.
For a low-light plant, you'd be fine without reflectors. They would likely help, but are not necessary.
If you want to increase the efficiency without spending the money on reflectors or trying to retrofit an existing fixture, painting the inside of your lighting fixture flat white is quite effective. A $3 can of spray paint supposedly gives quite good results. | a white reflector is next to usless compaird to a propper reflector, it would be a waste of $3 on a the paint.
Also, curved reflectors are only half as good as flat shaped reflectors since with curved reflectors they redirect half of the light back at the bulb making them only give an extra 50% of what flat shaped give | |
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March 29th, 2009
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| | Fish Keeper
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Originally Posted by Cordi a white reflector is next to usless compaird to a propper reflector, it would be a waste of $3 on a the paint. | Care to provide any proof of that statement?
I'll start: Quote:
White paint actually makes a better reflector in a DIY fixture than does tin foil
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I did some testing with a PAR meter, using a fixture for a 10 gallon tank, of mylar, aluminum foil and white paint. To my surprise, the mylar was the worst of the three. Aluminum foil and white paint were about the same, but my white paint was from a leftover spray can and not applied with any care. If I had used a good "ultra white" flat paint, I have no doubt that the white paint would have been the best. This is counter intuitive, to say the least, but just remember, we aren't trying for a shaving mirror here, but for maximum reflected light. Mirrors give true reflections, but don't reflect all of the incident light, nor do they need to. A good ultra white paint, out in the sunlight, is painful to look at. We don't need specular reflectivity for a light reflector, and it may even be a disadvantage, because it concentrates the reflected light too much. The white painted reflector also gave somewhat more even light at the substrate than did the mylar.
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About reflectors vs. white paint. I've done both, you can get good results either way
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The total reflectivity of a good white paint nearly equals that of silver, and is certainly better than any aluminized surface (mylar, foil or sheet metal).
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This exact same topic was discussed on one of my reef aquarium list a couple months back. One person, Dana Riddle (www.aquaticwildlife.com), has done many lighting studies on many types of light (MH, VHO and PC). He found that a white surface did indeed reflect as well as the metal reflectors. The only problem was that after sometime, 'painted' white reflectors turned yellowish and were less affective.
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A white diffusive reflector does provide a more modest gain, of the order of 1.6-1.8, not bad if we consider its cost (nothing). The aluminum foil reflector, on the other hand, is barely worth the trouble
| I could continue, but hopefully my point has been made. Unless you can offer any proof that painting the inside of a fixture white is "next to useless", I'll stand by my statement that it's better than nothing for someone who can't afford or can't retrofit a "proper" reflector. Quote:
Originally Posted by Cordi Also, curved reflectors are only half as good as flat shaped reflectors since with curved reflectors they redirect half of the light back at the bulb making them only give an extra 50% of what flat shaped give | Again, would you care to provide any proof?
Last edited by mathas; March 29th, 2009 at 12:40 PM.
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