# 65w CFL vs 48w T5HO (2 x 24w)



## loachers (Jan 30, 2010)

I've done a lot of research around this forum and elsewhere and can't come to a satisfying conclusion regarding if I should upgrade my lighting or not. I currently have a 65w Coralife Compact Fluorescent fixture (for planted tanks). I am thinking about purchasing a 2 x 24w T5 HO fixture to replace it.

I've read that T5's are more efficient, and also read they are the same light but just reflect better. I'm not sure what the actual truth is here. Would the lower wattage of T5's (at 48w) provide more/better light for my plants than the CFL at 65w?


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## gpodio (Feb 4, 2004)

I think you'll find they will be quite similar... If you're looking for an increase in lighting I'd consider a dual 55/65W CF fixture or tripple/quad 24W T5 unit. Ideally with individual circuits to allow you to run the bulbs independently... Or if they fit, add the dual 24W T5 fixture to the existing CF fixture...

Hope that helps
Giancarlo


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## Jane in Upton (Aug 10, 2005)

Gee, this seems to be a theme here....

I just posed a very similar question for a 20 g (24" wide) tank. 

I'd been running a 24" 2x55w CF fixture, which I must get rid of (LOUD fans).

I temporarily put back the 1x65w CF over the tank instead. But, it was looking like it wasn't quite enough light (some stretching) and then it went kaput.

So what would be a good replacement for a 2x55w CF with lousy reflectors (2 lamps packed in side-by-side, hugely inefficient) in terms of an HO T5 setup?

I basically have the same question as you, Loachers; I can't figure out if a dual 24w HO T5 fixture w/ excellent reflectors would suffice, even though the wattage is only 48 watts total.

I've been reading that the HO T5 have 25% better lumens output. OK, so does that roughly equate to 60w of the CF? 

I also read another post about a 20H tank, and with 96 watts of HO T5, some folks thought it would be too much light (or a VERY fast growing CO2/ferts system).

Thanks,
Jane


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## gpodio (Feb 4, 2004)

For the purpose of growing plants we can expect a little more lumen output per watt from T5 lamps compared to CFs but not enough in my opinion to make a huge difference. I still compare them watt for watt personally and I just keep in mind that the T5s are going to have an advantage due to efficiency and design aspects.

BTW, HO bulbs are not more efficient, actually they are less efficient than NO bulbs, they just handle more wattage per foot of bulb.

For example, comparing a few bulbs with similar specs:
1. 48" 32W T8 = 2950lumen / 92lpw
2. 48" 28W T5NO = 2900lumen / 104lpw
3. 48" 54W T5HO = 5000lumen / 93lpw
4. 48" 84W T5VHO = 7200lumen / 85lpw
5. 21" 55W CF = 4800lumen / 87lpw

As you can see, based on the wattage per length rating, a 55W compact fluorescent is indeed in the HO category, usually either a T5 or T6 diameter itself...

Technically speaking, a HO or VHO bulb has more resistant coatings on the filaments to better handle the increased wattage. One could say they are bulbs made to be "overdriven"  However the increase in heat causes some loss in efficiency, hence the T5NO is still the most efficient bulb in this category.

Hope that helps
Giancarlo Podio


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## DVS (Nov 20, 2005)

Hope this isn't considered off topic but this link has a different take on light use, you may find interesting, if you haven't already come across it.

http://www.plantedtank.net/forums/lighting/97622-par-data-selecting-t5ho-light.html


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## gpodio (Feb 4, 2004)

DVS said:


> Hope this isn't considered off topic but this link has a different take on light use, you may find interesting, if you haven't already come across it.
> 
> http://www.plantedtank.net/forums/lighting/97622-par-data-selecting-t5ho-light.html


That looks about right... a couple things to consider when reading such graphs:
- The difference between them is not huge... the same drop in PAR as moving the PAR meter 2-3" further away from the bulb.
- We're not comparing identical bulbs or identical ballasts. One can easily show a greater difference from two identical bulbs running on two different ballasts or the other way around, two different bulbs on the same ballast...

Overall I think it's in line with the data above... the PC having 200 less lumens than a similarly rated T5HO bulb and 5lpw less efficient.

PS. Unfortunately neither lumen or PAR are ideal values to compare efficiency... radiant flux is the only way to make a proper comparison, as difficult as that may be for us. Lumen is OK if the bulbs being compared don't have much emission in the invisible frequencies. PAR is even worse unless you know you are dealing with identical phosphors and spectral output.


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