# T5 tubes on T8 ballast



## [email protected] (Jul 17, 2008)

On my test of a single F54T5 running on one side of a two tube T8 ballast, the T5 bulb/tube lights up. It's not as bright as it should be, but that was expected since the ballast isn't rated for that wattage bulb. 

I would expect the F24T5 to light just fine. The F39T5 probably won't be as bright as it should be as the ballast is rated for 32 watt bulbs.


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## hyunbaw (Jan 18, 2006)

thanks for the reply. i'm glad i can make good use of a ballast laying around. i just wanted to make sure nothing would blow up!! 

ill keep you posted of any progress on my end..


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## terran2k (Feb 24, 2009)

that's the 2nd question I wanted to ask but some1 else asked it for me. 

any t5 tubes that are 20inch long to fit over my 10Gallon tank? around 30watts? maybe less b/c t5 put out more light than a t8 at the same watts?


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## Hoppy (Dec 24, 2005)

I suggest you not use the T8 ballast for T5 bulbs. The T5 bulbs are designed to start with a programmed start, as I understand, and that lets them be overdriven to the high wattage and brightness they have. But, a T8 ballast won't provide that starting condition. At best the T5 bulb would have a shorter life with the T8 ballast, and at worst it would only work a short time before failing.


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## hyunbaw (Jan 18, 2006)

hmm thanks hoppy, something to consider. Maybe i'll just go with 4 36" t8's. 

any quick comments on the best DIY "housing" material for 2 or 4 x 36" T8's? Good ol' lumber??


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## Hoppy (Dec 24, 2005)

A light fixture 36+ inches long is going to be heavy, but in order to do maintenance on the tank you will want to remove or at least move the fixture out of the way. So, the real challenge is making a fixture that can be moved to let you get in the tank without causing a hernia. Hanging the fixture is one way. Once you settle on how to do that, you can figure out much easier how to make the housing for the lights. Wood always works well, but you need to keep it thin to limit the weight.


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## hyunbaw (Jan 18, 2006)

heavy? really? 4 tubes and a ballast?


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## [email protected] (Jul 17, 2008)

hyunbaw said:


> heavy? really? 4 tubes and a ballast?


4 tubes and a ballast aren't heavy but the framing for a hood to contain them and reflectors of some sort can get heavy fast.


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## hyunbaw (Jan 18, 2006)

oh boy, maybe i should just buy a light setup. don't know if the fam would be ok with me attaching things to the ceiling :icon_roll


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## chuukus (Jun 17, 2008)

Hey there welcome to the forum. You want a neat idea for a diy light fixture? I found this guys site a few years ago wich has some cool diy projects but it also has a wealth of information. After building a light this way I think every light I build will be along these lines. check it out!http://www.malawicichlidhomepage.com/aquainfo/fluorescent_light.html
If your interested in aquariums look throught the articles this guy wrote I spend hours there reading everytime I learn something helpfull


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## Wasserpest (Jun 12, 2003)

Hoppy said:


> I suggest you not use the T8 ballast for T5 bulbs. The T5 bulbs are designed to start with a programmed start, as I understand, and that lets them be overdriven to the high wattage and brightness they have. But, a T8 ballast won't provide that starting condition. At best the T5 bulb would have a shorter life with the T8 ballast, and at worst it would only work a short time before failing.


Just to put this in perspective... programmed start ballasts are better for bulbs that are switched on and off frequently... like in bathrooms, refrigerators, etc.

For our purposes, an instant start ballast should not noticeably reduce the lifespan of a fluorescent bulb.

Workhorse ballasts, for example, are instant start, but recommended and widely used for T5 ballasts. I have used typical T8 ballasts for T5 bulbs with good results. Obviously you need to look at the wattage that the ballast can deliver.

For example, a ballast that can handle four 32 Watt bulbs will be alright up to 128W. So you could run 2 T5HO bulbs (54x2 = 108W) or four 24W bulbs. They might or might not be as bright as with a different ballast. If you use a four bulb ballast with two bulbs you can also try the OD trick (multiple leads to each bulb) to squeeze more wattage out.


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## dm76 (Mar 15, 2009)

I know this thread is a little old, but I ran across it and it is relevant to me. When you mention the weight of the hood, is that important as far as having to lift it off and on, or will it screw up the tank to have too much weight sitting on the top of it? I would imagine having 50 pounds sitting top of the tank not being good for it, but I can't imagine a wood canopy with lights weighing more than 10-15 pounds. Is that going to hurt the tank?



Hoppy said:


> A light fixture 36+ inches long is going to be heavy, but in order to do maintenance on the tank you will want to remove or at least move the fixture out of the way. So, the real challenge is making a fixture that can be moved to let you get in the tank without causing a hernia. Hanging the fixture is one way. Once you settle on how to do that, you can figure out much easier how to make the housing for the lights. Wood always works well, but you need to keep it thin to limit the weight.


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## [email protected] (Jul 17, 2008)

Wood canopy's get heavy fast. Particularly when built by most DIYers. 
Off the shelf at most Home Depot type stores, the selection of inexpensive thin wood is not good. Add the fact that most inexpensive plywood isn't flat and the need for 3/4" this and that and pretty soon it takes two people to lift the canopy for a 48" tank.


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## dm76 (Mar 15, 2009)

Ok, I guess it does add up. But is the concern here the difficulty of being able to lift or move it, or is the concern that it will hurt the tank setting that weight on it?


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## Hoppy (Dec 24, 2005)

I wouldn't worry about the weight of a hood, as long as it rests on the ends, front and back glass of the tank - on the rim, in other words. Of course there is a limit to how much weight it would hold, but I doubt that a DIY hood that isn't made from 1 inch or thicker wood would damage the tank.

The weight problem is that if it is a bother to remove the hood you will do far less daily fluffing of plants, plucking dead leaves, wiping odd patches of algae on the glass, etc. And, that can become a problem. I once had a 120 gallon tank with a hood that took two people to lift off, and it was still difficult. That tank almost never had a hand inserted for minor "maintenance". (And, it soon showed it.)


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## dm76 (Mar 15, 2009)

Ok good, that clears it up. Ideally, I would like to make part of the top of the canopy be able to open, and the rest of it stationary with the lights mounted to it. Since my tank is 18" wide, I hope leaving a 6" opening to open is enough, then the lights can stay on while doing cleaning, etc.


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## Wasserpest (Jun 12, 2003)

This is going pretty far OT, but anyway, you can build a two-part canopy, connected with a piano (or other) hinge.

http://www.plantedtank.net/forums/equipment/27727-new-canopy-my-100-gal.html

I built that one to replace a canopy I made out of 3/4 plywood... for that 100gal tank it was a major act to lift it up, just like Hoppy described.


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