View Full Version : T5 or T8 ??

09-01-2010, 12:37 PM
When I got some shop light fixtures for the tanks, the sales person told me that T8 was the latest and best, replacing....whatever. The last few days I started noticing every one is getting T5's.
Do I need to return the T8 fixtures?
Which are the most cost efficient?
which one will have the longest life with easy to find bulbs?

09-01-2010, 03:06 PM
T5s are newer, smaller, and more efficient (light per amount of energy used) that T8. So you'd like replace a 32W T8 with a 28W T5. So you'd shave 1/8 off your energy cost. Or you could even replace 2 T8s with a 1 54W HO T5 (high output). Good for really tight spaces. T5s and their fixtures are pricier than T8s now, but prices are expected to fall over time. T5 bulbs last about as long as standard t8s, but you can buy "long-life" T8 bulbs that last longer. I'd assume longer-lived T5 bulbs will come later. Right now T5 bulbs are harder to find than T8. In the future, I'd expect T5s to get easier and T8s to get harder to find.

reference: http://www.lrc.rpi.edu/programs/nlpip/lightingAnswers/lat5/pc1a.asp

Last time I looked for shoplights, the T5s fixtures were a lot more money. If they come down into your price range, I think you should go with T5s. The only drawback to them I see is that they run hotter (95F vs 77).

If you really want the lights of the future, you'd go to LEDs, but I think T5s are a good "forward-compatible" light. T8s are still fine, but T12 are on their way to permanent phase out.

09-01-2010, 03:35 PM
Are you also saying that I can't use T5 bulbs in a T8 fixture, because the bulbs are different sizes?

09-01-2010, 03:58 PM
Yes. T12s and T8 have the same pin set and you can put T8s in the T12 fixture, but you can't do this with T5s. The pins are closer together and the bulbs are shorter. To convert a fixture, you'd need to swap out the ends (socket the pins fit in) and possibly the ballast as well.

So only buy T5 bulbs if you buy a T5 fixture. Some of the T5 "undercabinet" lights are approaching affordable and they come with the connecting cord so you can chain them.

If you can't find cheap T5 fixtures, go ahead and use T8s.

They already make LED "drop in" replacement for T8s. When prices drop, you will be able to get more efficiency just by changing a light bulb and removing the ballast. Right now $59 dollars a bulb is too rich for me even though the use only 40% of the power. http://www.amazon.com/LED-fluorescent-replacement-ballast-2043WH/dp/B002P3FQI6

I really support being as efficient as you can afford to be as power is the most expensive ongoing fish-keeping cost. Add to that the fact that if you draw too much juice, you may need to upgrade your electrical panel, and spending a bit more upfront can pay off in the long run.

09-01-2010, 04:09 PM
thanks for the expert advice.

09-01-2010, 04:11 PM
"expert" lol. Google is my friend

09-07-2010, 04:30 PM
what size fixture are you looking at beatty? i have a 2x24watt t5 fixture i'll be selling soon. let me know if you're interested

09-07-2010, 04:46 PM
since I dont have any plants...yet, I am looking for length to fit over tanks. 30 in, 36 in, 48 in, bulbs that will fit in OLD 10 gal hood.
I am planning on getting low light auction plants, and putting them in pots, in BB tanks. Will this work?
I think I am the only person to beg for duck weed, and other floating plants, havent been able to keep them alive...I dont even have alage.

09-08-2010, 11:14 AM
I have upgraded my older fixtures to T5 & been very happy with them, especially for plants. I tried T2s over my 55 & was not pleased with them at all and switched to T5 as soon as a I found a reasonably priced used fixture. If you want to have plants, T5s will work better than T8s & require less wattage.

Larry Bugg
09-08-2010, 01:14 PM
It really depends on what kind of plants you want and how much maintenance you want to put into it. The more light you put over a tank the more you increase a need for more Co2 and ferts. With planted tanks it all about maintaining a balance of these three elements. Increasing light without increasing Co2 and ferts is asking for algae problems. Now if you are going to run the increased light for a shortened photoperiod then this plays into it also. I have low light planted tanks that I use shop lights over wtih T12's and I only run one of the two bulbs. If I have both bulbs running then the algae kicks in. I also have run low/meduium light planted tanks using T5's but I dosed with excel for Co2 and dosed flourish for ferts. You will have to find the correct balance with whatever you choose. MORE is not always better. We learn this the hard way when it comes to planted thanks. My very first planted tank was a 55 with 4x65 CF and DIY Co2, that was a hard lession learned. And I wondered why I had algae problems..............................It didn't take long to learn that I had to have pressurized Co2 and even with that I had to reduce the photoperiod by half on two of the 4 bulbs. Balance!

10-29-2010, 08:29 AM
Aquarium 200 cm x 50 cm x 60 cm height, lit by six 39-watt T5, notice the power tubes. Lighting 12 hours a day


10-25-2011, 09:51 AM
Blowing the dust off an old post here: I am looking for a T8 replacement bulb about 32-36 watts. I think I need an 18" bulb, but when I measure it it comes to 18" from the outside of the mount end to the outside of the mount end--the bulb itself is about 16.5-17 inches. I assume "18 inch bulb" means this 17" bulb??

Does anyone make a 32-36 watt 18" bulb? All I have found (so far) is 15 watts in 18".