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Question about T5 & T8


edmondsng

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Before you buy T5 over T8, have a look at this article. It says for 25C temp, they are the same efficacy. Given T8, you can find more of the colours you would want.... Think about it.

http://www.lrc.rpi.edu/programs/nlpip/l ... t5/pc7.asp

T5 high output (T5 HO) lamps have greater luminous flux per unit length than standard T8 lamps, but the light output of standard T5 lamps per unit length is almost identical to the standard T8 lamps. If, however, this question requires a more precise answer and lamp efficacy needs to be taken into account, several factors affecting the light output-and therefore efficacy—should be considered.

One of the most significant factors affecting lamp light output is ambient temperature. Table 1-7 summarizes light outputs and efficacies of nominal four-foot standard T5, T5 HO, and standard T8 lamps. Manufacturers usually provide light output data at the optimal temperature for each lamp type in their catalogs: 35°C (95°F) for the standard T5 and T5 HO lamps and 25°C (77°F) for the T8 lamps. Light output data for T5 lamps at 25°C (77°F) and for T8 lamps at 35°C (95°F) are also available from manufacturers, however. Table 1-7 shows that, at 25°C (77°F), the light output of T8 lamps is higher than the standard T5 lamps. At 35°C (95°F), however, the standard T5's light output is higher than that of the T8 lamp. With respect to lamp efficacy, the standard T5 lamps are more efficacious than the standard T8 lamps at 35°C (95°F), but the two types of lamps are nearly identical at 25°C (77°F). The lamp efficacy of T5 HO lamps is higher than the T8 lamps but lower than the standard T5 lamps at 35°C (95°F), and it is the lowest at 25°C (77°F).

( all of the above is from the metnioned website, lighting reasearch center)

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Also, the t5 ho tubes mean you need less of them, so getting more of the usable light out of them into the tank is easier. If you have to put in so many tubes that they are virtually touching, then a lot of light will just hit the next tube over and be absorbed by it, instead of hitting the reflector and then the tank.

Also, T5's are slightly shorter so when you make your hood without thinking about how the lights going to fit, they will fit whereas a t8 will not. t5 ho batten fittings are a lot more expensive then a cheap t8 one, but comparable to a decent t8, so you gain in the lower number of fittings you need unless you like buying the cheapest thorn piece of crap that there is.

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I have just purchased 4x t5ho for my new tank. I went with the recommended 3x blue and 1x white,however when they arrived one of them was a red one. Curiosity got the best of us so we had to try it out. It gave a sort of pink tinge to the tank that didnt look that good so we returned it.

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