How to convert 2x18w T5NO into 1x31w T5HO - The Planted Tank Forum
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post #1 of 5 (permalink) Old 07-19-2011, 06:35 PM Thread Starter
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How to convert 2x18w T5NO into 1x31w T5HO

Okay, anyone who owns a 20 long knows that when it comes to lighting, it's slim pickins. For the longest time the best option was the infamous Coralife t5no strip light, which does work very well for lowish medium light tanks, but even using 2 of them together doesn't quite put tanks into the high light category. Then if you step up to T5HO, you generally only have options that result in too much light, or the bulbs only being 24" long over a 30" tank.

So after weighing the options recently, after my 2 coralife fixtures took a dive, I decided what I really needed was a single, well-reflected T5HO tube. Seems simple enough, but the 24w ones are too short while the 39w ones are too long. Being as picky as I generally am, I decided I wanted to go with 31w tubes, since they are the same length as the tank.

The only way I could accomplish this would be to make the fixture myself. So I gutted the coralife strip light and retrofitted it with a high output ballast, then fixed it up so it would take a single tube instead of 2. I took pictures along the way, but I didn't start until after I had taken the endcaps off. But it was very easy to disassemble, and only required a screwdriver.

Here we go...

I started by taking the ends off the strip light, cutting the wires leading to the end caps, cutting the wires leading to the switch, and then pulling the ballast out. To pop the switch out all it took was a flathead screwdriver.

Now, here is everything after being all pulled out and laid out together on the floor:

Then, what I did to obtain the high output ballast for this task is I bought a single-tube strip light in the 39w variety from the hydro store. It was actually much cheaper for me to do this than it would have been to order a workhorse ballast or something like that. And once I brought it home I proceeded to void its warranty promptly.

I started by popping the switch off so I could clip the wires:

I then removed the ends of the strip light, and pulled the ballast out of it, keeping the end caps attached this time. I wasn't sure if I would want to use those instead of the ones that came with the coralife strip light.

Here you can see the difference in size between the normal output ballast and the high output ballast. Believe it or not, the HO one was much smaller!

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post #2 of 5 (permalink) Old 07-19-2011, 06:36 PM Thread Starter
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Then it became time to re-center the end caps on the strip light ends. Since the coralife came with 2 tubes, closely squished together, I needed to remove the plastic molding they had in place so I could center a single one in their place.

I glued the end caps to the plastic ends using regular old super glue, then held it in place with a clothes pin. I then stuffed the new ballast and end caps into the old strip light, which was relatively easy since it was smaller than the original ballast. Keep in mind, the new ballast originally came wired up for a 36" strip light, so it was much longer than I needed it to be, so I had to stuff a lot of wiring in the end there:

And here's what it looked like all properly closed up again:

Then here it is with the tube installed, then turned on:

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post #3 of 5 (permalink) Old 07-19-2011, 06:37 PM Thread Starter
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Everything seems pretty evenly lit to me! After the coralife strip lights went out I had to switch over to a 2x24w grow light fixture, which provided very intense light, but it was obviously shadowed on the sides of the tank. Now that I have a single 31w tube in here, the tank is evenly lit, while still being brighter than the 2x18w bulbs were, but not as bright as the 2x24w were.

The only complaint I have at the moment is that the only color spectrum available in 30" at the LFS was the 10,000k variety, and now that I'm overdriving it ever so slightly, it seems too blue to me. I think ideally here I should be using a 6500k bulb.
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post #4 of 5 (permalink) Old 07-19-2011, 10:39 PM
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Wow that looks good. I ran in to the 30" problem and ended up buying a 30" 2 bulb t5ho, but it had 21" bulbs. It works, and doesn't have shadows, but I like yours better.

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post #5 of 5 (permalink) Old 07-25-2011, 08:19 PM Thread Starter
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Thank you. I've been testing it over my 20 long for a week or so now, and it seems to be doing its job very well. Much better than the 2 NO bulbs did, and not as accelerated as the 2 HO bulbs did. I think I found my perfect middle ground!

It lights the tank evenly, I see no shadows, and the glosso is growing like the weed it is! And now that I have a low-profile strip light that lights my tank evenly while not taking up too much space up top, I can open the lid without moving anything around!
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