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This DIY CFL OK?

2370 Views 13 Replies 4 Participants Last post by  Hoppy
Wanted a clean way to have CFLs without spending any money but I was a little worried about heat so I thought I would check here before I melt anything.

Tank is 10 gallons and it came with a hood like this
http://www.aqueonproducts.com/assets/015/26916_400wh.jpg

I also have one of these that a friend gave me
http://www.aqueonproducts.com/assets/010/13542_400wh.jpg

I know I can put CFLs in this one, but I don't like this design with the little opening in the front. I disassembled them both and the guts of the Incandescent light will fit in the Fluorescent strip, but there is only about 1/2 inch between the bulbs and the housing and clear plastic under the light. I was just going to cover the inside with aluminium foil for a reflector. This won't cost me anything, and it allows me to keep my full access front hood while getting two CFLs but like I said, I'm worried about the heat. Do you guys think it will melt something without ventilation?
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Well, I got impatient and started assembling since no one had responded yet. Only problem is I broke the On/Off button for the lights I was going to use. It is built in to the bulb socket, and didn't seem to be usable anymore. So after a quick run to Lowes and $15 dollars later I put two new light sockets and two 13W CFL 6500K daylight bulbs in the fluorescent housing and it works perfectly. I'm going to keep an eye on it for a while for the possible heat issue with them being kinda cramped in there, but so far doesn't look like it will be an issue. After being on for about an hour, the bulbs are hot, but the aluminium foil seems cool, so I think it's blocking most of the heat off the plastic housing and my wiring that's behind it.
13W should be okay... as long as there is some passive ventilation (holes) going on. If you cover all of them with foil it might get very hot in there and reduce the lifespan of the bulbs.
There isn't really any ventilation right now. I was thinking about drilling some holes in the back and sides, but I didn't want it to shine alot of little bright dots on the wall behind the light. If it becomes a problem I guess I might have to do it any way. Just keeping a close watch on it for now. If it works I'll be happy with it. From the outside it looks completely original and it gives me 2.6 WPG which I think gives me a much wider range of plants to start this tank. Plus the scape has one area thats only about 5-6 inches from the bulbs so I may try some higher light plants for that section.

I'll update if I burn down the house. Until then I'll be working on some cheap CO2 solution. Most likely a paintball tank setup.
That should be giving you about 40-50 micromols of PAR, which is very good low to low medium light. If the aluminum foil reflectors surround the back and sides of the bulbs, and if you can see two images of the bulbs reflected from the foil, you approximately double the light you get from the bulbs. (The 40-50 micromol estimate assumes the reflectors are that good.)
Do you need to keep the foil perfectly smooth when you use it? I didn't think about it when I used it, but now I'm wondering if all the wrinkles in mine makes a difference. Thanks for that little numbers breakdown Hoppy. Are you saying that will be the readings at the bottom of the tank, or in the higher section of the scape that is closer to the light that I mentioned? I was reading some threads about how much the distance from the light can change the amount that reaches the plants pretty noticeably, so Iwas hoping being only 5-6 inches away would put me a little higher. Maybe higher side of medium light. Either way, it is what it is for now. I want to make a high light tank later, but I've still got a lot to learn about balancing everything first, and gotta get some CO2 running.
Aluminum foil is really a horrible reflector. Just a tad better than black plastic. If you really want to use foil, perhaps silver Mylar (as used for those happy-something balloons) is a better choice. And painting/spraying the inside with bright white color would be way better.

Whether the aluminum is wrinkled or not, not much difference IMO... Don't think there is any chance of doubling the light that goes into the tank.
I have 2 of these CFL bulbs in a 24" incandescent strip light. The bulbs screwed perfectly into the supplied 2 socket with on/off push button fixture .

I found a roll of polished Myler adheisive tape in Lowes and covered the entire inside of the plastic housing with the tape. I did not obstruct the vents though. After 12 hours running the light assembly is barely warm.

Although I have not measured the light output I can assure you that the light intensity can only be characterized as brilliant.

I am using this light on a 20 g Hi tank with co2 injection. The plants are growing like mad!
Aluminum foil is really a horrible reflector. Just a tad better than black plastic. If you really want to use foil, perhaps silver Mylar (as used for those happy-something balloons) is a better choice. And painting/spraying the inside with bright white color would be way better.
I was reading a forum where someone was testing with a par meter, and to their suprise the same light was giving higher readings with aluminium foil over mylar. Sounds odd but that's what the meter said. Based on that, and mostly that I already have the aluminium foil, I just used that. Plus, it allowed me to cover all of the wires so they wouldn't block any of the light, which I couldn't do with white paint very easily. I can't remember what forum it was on, but if I can find it again, I'll post a link. They were testing alot of different scenarios of different types of lighting, reflectors, and height of fixture. Very detailed, but I did so much googling that day, that I can't remember all the different forums I was reading.:icon_roll

I think I might start working on something from scratch later. I'd like to get a glass top eventually, and take my time making somthing nice with a little more light later. I think I mostly want to do it just for the fun of it cause I like tinkering. I worked as a mechanic for 5 years, and I think I really miss it sometimes. Maybe it's worth making less money to do something you enjoy, but then again I never felt that way back then when they paid me.
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Aluminum is the most reflective metal you can use for a reflector. As long as it isn't so thin you can see through it, it will be the best reflective surface you can get. Aluminum foil is perfect for this use, better than aluminized mylar, because that usually has too thin a coat of aluminum, and a bit better than brilliant white paint. Winkles only prevent you from using the foil as a shaving mirror, they do nothing to reduce the reflectivity. You can use either the dull or the shiny side of the foil and get essentially equal reflection from either. Don't trust your intuition on this.
High quality polished specular aluminum is completely different from alu cooking foil. One is indeed the best material for reflectors, the other... not.

I could be totally wrong though. I haven't measured PAR of cooking foil. But I have used it in reflectors and removed it quickly because visible light reflection was horrible.

This reminds me of the discussion where folks would insist that mirrors are bad reflectors, because the light has to pass through a sheet of glass, twice.

I'll go with my intuition and eyes on this one. :icon_mrgr
High quality polished specular aluminum is completely different from alu cooking foil. One is indeed the best material for reflectors, the other... not.

I could be totally wrong though. I haven't measured PAR of cooking foil. But I have used it in reflectors and removed it quickly because visible light reflection was horrible.

This reminds me of the discussion where folks would insist that mirrors are bad reflectors, because the light has to pass through a sheet of glass, twice.

I'll go with my intuition and eyes on this one. :icon_mrgr
I agreed with you until I used a PAR meter to demolish my intuition. :icon_mrgr
I've seen people test mirrors as well and come up with low readings. Apparently visible reflection is a very different thing from actual light reflection. This is why I never trust my intuition on things that I don't already know alot about if I can find some type of testing to prove otherwise. I'm too often wrong. I would have thought a mirror would be the best thing to use. Makes sense in my head because it's entire existence is based on reflection, but the testing I've seen proves otherwise.
A mirror for combing your hair, shaving, applying make-up, etc. can reflect 50% of the light and still be a great mirror if the reflection is undistorted. But, 50% reflection is very poor for a light reflector. A light reflector can distort the reflection totally out of shape, but if it reflects 90% of the light it is a very good one. Unless you are trying to use the reflector to focus light, distortion is meaningless.
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