# T8 hood converted to 4x CFL



## majorwoo (Dec 22, 2012)

So I decided I wanted more light. I had a 2xT5NO and the original single T8. I was debating running both, when I decided that I might as well just make the leap.

I took my old T8 hood (it helps if you have a beautiful assistant)









I took everything apart (one of the fun parts)

















I removed the existing reflector:









And hammed it out, then rebent it to fit the shape of the hood after the old ballast, starter, etc were removed (you can see the scraps of metal where I cut it as it was too long after reshaping):









I went to Lowes and bought 4 generic light fixtures (Servalite H#884413 $3 each), a bag of wire nuts ($2) and a pack of bolts($2)/nuts($1)/washers($2) that fit the mounting hole in the socket. I drilled 4 holes where I wanted the lights to be (spacing them out roughly even) and started wiring the socket in:









I kept all the wiring under the reflector, and after putting it back in the hood roughly to make sure it fit:









Then tightened everything down and installed my bulbs.









I ended up with 4x 14w @ 5000k, I may look around for some other bulb options but the research done seems to indicate the color rating on the CFL's isn't as important.

I took some before and after shots of the tank itself, but the lighting difference in the room and the dust leftover from the Flourite sand attributes to some of the color differences that you see in the picture.

Before:









After:









Having caught the DIY bug, I believe I need a pressurized CO2 system next, and I might modify my light in the future to have a lunar light like I saw some people using.


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## Michael (Jul 20, 2010)

I am a big fan of spiral CFLs for economical lighting. They produce about twice as much useful light if mounted vertically rather than horizontally, but you didn't have a choice in this retro-fit.

Please keep us updated!


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## majorwoo (Dec 22, 2012)

Michael said:


> I am a big fan of spiral CFLs for economical lighting. They produce about twice as much useful light if mounted vertically rather than horizontally, but you didn't have a choice in this retro-fit.
> 
> Please keep us updated!


I had seen some references to vertical vs horizontal - but I thought it mostly came from the reflector being larger and/or better quality in vertical mounts - like this:









Is there another advantage to vertical mount? I probably won't go that way as I could easily build my own hood, but i wanted it to stay within the confines of the wooden canopy that keeps the wife from screaming it's ugly


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## majorwoo (Dec 22, 2012)

It seems one of the CFL's was defective, as the bulb was cracked this morning. I returned the pack of 4, and I'm now running 4x 13w 6700k (which they didn't have yesterday when I looked for ~6500k)

So I'm happy it broke I guess


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## Michael (Jul 20, 2010)

Yes, it has to do with "restrike" because some of the light produced travels back into the CFL. The best discussion I've seen is at http://www.plantedtank.net/forums/showthread.php?t=85667&page=2

Scroll down and read the posts by i4x4nMore. He shows PAR tests comparing output from vertical vs. horizontal mounts using very similar reflectors.

BTW, where do you get vertical mount reflectors like that? I want some!


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## majorwoo (Dec 22, 2012)

I just grabbed that picture off the net, but Lowes here outside Atlanta had something similar when I was there. I don't know if the reflector was as good as that one looks.

Very interesting about the orientation, I am surprised to see such a large difference! I also find it interesting that he seems to be comparing the height above the water, vs the height from the substrate - now if the same tank/substrate is used then it would be the same but it makes me wonder about the difference of "air" space vs "water" space and whether that is significant or just the way he choose to write it up.


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## Michael (Jul 20, 2010)

Air space and water space are very significant. Water absorbs light energy very quickly, so even shallow water prevents penetration of the light to the substrate. In contrast, air absorbs so little energy that the amout is negligible in the distances we are talking about.

For example, if you measure PAR at the surface of the water in your aquarium, you might get reading of 600, but at the substrate 16" below the surface, it might be only 50 or 60. If the aquarium was empty and you were measuring in air, the PAR would still be close to 600.

For another example here are some PAR measurements taken in my backyard pond in full sun at noon in September.

Just above the surface--1,700
12" below the surface--1,200
24" below the surface--800

If the pond had been empty, the PAR would have been the same at all positions.

This important for many reasons, one of which is that certain manufacturers of aquarium lighting publish PAR data, but only for measurments taken in air, not water. This information is almost useless.


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## majorwoo (Dec 22, 2012)

I definitely understand that the distance from the light is an important factor - but there is more here at play then I am fully understanding. Take for example a light on top of a 24" tank. It has been shown that raising the light 12" off the tank has an enormous impact on the lighting level at the substrate - so although the PAR readings at 36" (the light) and 24" (the water surface) may be the same the actual loss of light seems tied to the overall distance from the substrate. Now I suspect that 24" of water + 12" of air provides less light loss then 36" of water - so this is what I'm not understanding - if the PAR reading at 24" (the water surface) is roughly the same as the PAR at 36" (the light) why do we get such a difference at the substrate level simply by raising the light over the tank? Perhaps because less of the light actually makes it into the tank and more is lost over the edges? It would seem that the PAR at the substrate level is relative to the total distance from the light - which I could accept that we are saying air provides a negligible loss so if the PAR at the 24" mark isn't reduced why is their additional loss by the time we reach the substrate?

Hopefully I've not worked this so poorly that I've lost you.


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## Michael (Jul 20, 2010)

This is a tricky subject, and I haven't done the best job of explaining it. Your questions are very good, and I'm glad you are asking them!

Simple distance from the light fixture does make a difference whether in air or water. But the light decreases much more quickly when traveling through water than air. Moving a light fixture farther from the surface of the water does mean that less light is striking the surface. But the big decrease in light still happens below the surface.

See my comments below.



majorwoo said:


> I definitely understand that the distance from the light is an important factor - but there is more here at play then I am fully understanding. Take for example a light on top of a 24" tank. It has been shown that raising the light 12" off the tank has an enormous impact on the lighting level at the substrate - so although the PAR readings at 36" (the light) and 24" (the water surface) may be the same the actual loss of light seems tied to the overall distance from the substrate.
> *It is tied to the overall distance from the substrate, but the distance the light travels through water (instead of air) is much more important.*
> 
> Now I suspect that 24" of water + 12" of air provides less light loss then 36" of water
> ...


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## majorwoo (Dec 22, 2012)

Thanks Michael. I appreciate your help - as much as I enjoy reading the work of people like Hoppy at a certain point it helps immensely to go back and forth with someone who understand more about it then I do. I am going to look for a club around Atlanta as I would like to get some actual readings on my own tank.

On a bright note? I was doing some reading this morning and realized that when I bought the tank it was mislabeled - it's not a 55, it's a 65 gallon tall - 36x18x24 gives me 67 gallons. So I just "gained" 10 gallons


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## Michael (Jul 20, 2010)

I love that size tank! The 18" width makes it much easier to design than the standard 55, and proportions are really pleasing.


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## Chris. (Dec 22, 2008)

I'm looking at doing this for my already retrofitted fixture on my 38g. Right now it's using 27Wx3 6700K fluorescent bulbs. Some of my plants have not been thriving on this setup like they did on my 20 gallon running power CF bulbs so I'm going to try this out. Here are the bulbs in it now.


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## alanle (May 8, 2013)

You might want to spray paint the reflector with chrome paint. It helps

Sent from my Nexus 5 using Tapatalk


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