# When to change T5 HO bulbs



## Emily6

Hey folks- I'm about 5 months past my first T5 fixture purchase and I was wondering at what point to change the bulbs. I read somewhere that it's around the same as CFL bulbs- 5-6 months. This doesn't impress me since i bought the fixture for the savings among other reasons (though the bulbs are cheaper). But I noticed my riccia just seems to be pooping out and giving in to some algae even though I moved it closer to the surface. Not sure if T5 looses spectrum the way CFL does and the riccia is my indicator. Everything I've read suggests T5 is the bees knees so please advise.

Thanks!


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## niko

Keep in mind two things:

1. Not all bulbs are made the same.
Some will last much longer, some will not really produce the light (intensity, spectrum) they should.
That goes for any type of bulbs.

2. You can use the same bulbs for years.
Your plants adapt to changes in the conditions very well. As long as the change is gradual the plants will adapt to just about anything. You could grow high light plants with half the light everybody says is needed. You could use a bulb for 10 (ten) years.

Also - get in the habit of questioning everything that you know for sure about your tank. Your plants don't grow well? Double check the CO2 level, the temperature, the flow, the nutrients, the light period (is that timer really working as you think it is). You get the idea.

--Nikolay


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## TonyVideo

I wouldn't change them until they go out. Sure as they age they me not be like new but as long as the plants still look ok why spend the money.


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## bartoli

niko said:


> 2. You can use the same bulbs for years.
> Your plants adapt to changes in the conditions very well. As long as the change is gradual the plants will adapt to just about anything.


I have used bulbs that lasted for a number of years, usually until they burnt out. But when a bulb suddenly dropped its intensity so much that it was very obvious to the naked eyes, I retired the bulb.

BTW, a light intensity meter is a cheap and easy way to objectively quantify the intensity emitted from a bulb. It helps to cut down on the unnecessary toxic environmental waste.


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## Newt

Are they T5HO (high outout) or just T5?

Makes a BIG difference.


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## Seattle_Aquarist

Hi Emily6,

I thought you had a good question so I did some digging and this is what I found.



> Table 1-3 illustrates features of four-foot standard T8 and T12 lamps. Standard T5 and T5 HO lamps have a rated average lamp life of 20,000 hours, the same as most standard T8 and T12 lamps. New prolonged-life T8 and T12 lamps have lives of 4,000 to 10,000 hours longer than T5 lamps. (Table 1-3 excludes these lamps.) The lamps in Table 1-2 all use RE80, a rare earth phosphor with a color rendering index (CRI) value of 85.


20,000 hours sounds really great; but that is the life expectancy under optimum conditions. Useful life is usually about 80% of the life expectancy, after that there is degradation of the bulb output. Also the number of "on / off" cycles, heat (and cold), and moisture can further shorten a bulbs life.

BTW, 16,000 hours equals 2000 days (or 5.47 years) at 8 hours of use per day.


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## bartoli

Seattle_Aquarist said:


> I did some digging and this is what I found.


Very interesting! Table 1-2 gives the initial light output and the mean light output (i.e. light output at 40% of rated lamp life). A little calculation of mean over initial gives a rough figure of 94%. That means after using a bulb for 40% of its rated life, it still generates at 94% of its initial output.

Since the average lamp life of T5 and T5 HO is 20,000 hours (or 4.56 years with a 12-hour use per day), after 22 months (40% of 4.56 years gives 1.82 years which roughly translates to 22 months), a bulb still generates at 94% of its initial output.

Now, considering the common recommendation of replacing a bulb every 6 to 12 months, that is an awful awful waste of resources (and generating toxic waste along the way).

Does a tank really need a new bulb when the existing bulb is still generating at 94% of its initial output?


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## Emily6

Wow, thanks for the terrific response! For ha-has I bought new bulbs on Ebay to see if I could perceive a difference between new and old (worst case scenario, I'm ahead of the game when I actually need new bulbs if there's no current difference.)

Anyway, seems you all are right- I can't see any difference. So I'm relieved that in the future I don't need to be changing these like I did the CFL bulbs. 

BTW Newt, it's a T5 HO- the same fixture previously discussed here from Ebay that seemed too cheap to be true.

Though I did due diligence to see why my riccia is slowing down and I'm left with my water pH affecting CO2. I recently re-calibrated my Milwaukee pH meter to find it way off (reading 6.5 when it should have been 6.1)- so I'm thinking since I recalibrated the meter, the CO2 hasn't been on a much. Since I have tap water at a steady pH of 8, with every water change the CO2 stays on longer so this should get better with time. I think these last couple weeks have been enough to give the algae an edge.


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## fishyjoe24

not all bulbs are made the same, get quality bulbs.. 3 inportant factors to never skip out on.. lighting,filtration,and heating.


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## Emily6

What's a good brand in your opinion? I usually end up shopping by price. I find that I have trouble consistently finding the same bulb every time I need it. The LFS closest to me is still 45 minutes away so I tend to buy online since at least it won't be a wasted trip if they don't have what I want.


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## bsmith

GE or Giesemann.

Here is where I purchase my bulbs from. I cant find anywhere cheaper after shipping.


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## Emily6

Thanks- these don't seem all that much more expensive than what I'm buying now. Though I haven't bought enough to form an opinion yet.


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