# T5's vs. CF



## DJKronik57

Are T5's really better than CF? Is this an area where watts fail to describe the power of the light to grow plants and T5's really are brighter for lower watts? Or is their main benefit their small size so you can fit more over a tank? Just wondering where T5's fit into on my scale of aquarium lighting for plant growth: 

::worst:: incandescent-->normal output fluorescent-->compact fluorescent-->metal halide ::best::


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## andrewwl

Bump... I, too, would like to know the expert opinion on this.

Added questions:

How hot do t5's get relative to the other types of lights?

What's hotter? 96W of PC or 70W of halide?


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## John N.

Lighting setups are a very controversial subject and there are many opinions out there as to what is the best lighting system. There are many factors that affect a particular lighting system's performance such as size of the tank, types of plants, positioning of the lights, etc.

All types of lighting systems have their pros and cons. T5 bulbs have lower power consumption and less heat output where a PC bulb has higher light output but can run hotter and consume more power.

I asked Kim Bryant of ahsupply.com DJK's original question and here is the response.


Kim Bryant said:


> With fluorescents, the smaller the diameter of the tube the more efficient they are per watt.
> 
> The 36W and 55W Compacts we sell have twin T5 tubes. They are just in a compact format with all the connectors at one end, as opposed to linear T5s which are single tube and have connectors at both ends. We like the compact format primarily because you need fewer sizes to fit a greater variety of tanks.
> 
> A don't agree that MH are the best though they are useful when you need to fit a lot of watts in a small space or when you want to have suspended lights. Other than that I don't see that they are worth the hassle. Light is light when you are talking about a given wavelength. It is not as if MH produce some wavelengths that you can't get just as well with fluorescents.
> 
> Regards,
> Kim Bryant
> A H Supply


So based on this information:

*From Best to Worst*
1. Metal halide 
2. T5 (slightly better)
3. CF compact flourescent bulbs
4. NO normal output fluorescent 
5. Incandescent

I hope that helps,

-John N.


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## DJKronik57

Wow, thanks John! That's exactly what I was looking for. In other words, it doesn't make sense to "upgrade" to a T5 system when I have a perfectly good CF system. Plus, T5 systems tend to be more expensive for what you get, right? Now...I just noticed some very neato LED systems on the Green Chapter website, but I'll leave that discussion until they are available in the US! Thanks again.

-Andrew


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## AaronT

It should be mentioned that we toss the term T5 around here a lot and omit the HO part. Only the T5 high output bulbs are comparable to power compact lamps. Which one is better? Well, technically they are the same thing. Power compact bulbs are essentially high output T5 bulbs bent in half. 

So what's the advantage of a linear T5 HO bulb? The profile! This is where good reflectors enter the equation. Using parabolic reflectors greatly increases the light entering the aquarium and cuts down dramatically on the light reflecting back into the bulb causing it to heat up and become less efficient (restrike). The slim profile of a linear T5 HO bulb works better than a power comact bulb even if both are used with parabolic reflectors because the bulb is so thin most of the light shines into the aquarium and not back into itself.


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## Gomer

Having run spiral compacts, Power Compacts, and T5HOs, I will always go to a T5HO as long as there is a good reflector for them


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## ruki

Yes, T5 sized bulbs are designed to work well with a good reflector.

What sucks, yes really, really, really sucks about PC lamps is that they bend back into a U shape. This means that along the inside edge light will go out of the lamp and and back into it on the other side of the U. This wastes light. It creates extra heat. No way to get around this.

The linear nature of the T5 sized bulbs means that a reflector theoretically can direct almost all of the light down into the tank. Since it is 5/8ths of an inch the reflector can be much smaller than the 8/8ths of an inch T8 or 12/8ths of an inch T12.

Also, T5 HO bulbs are designed to be overdriven. They seem to run more than a bit cooler than PC bulbs, but that just might be because well designed integrated metal reflector/hoods act as a great heat sink. (No fan in my TekLight)

T5 NO bulbs are more efficient than T8 NO. So, if you want to save a little electricity use T5 instead of T8. (These have recently hit our market.)

T5 HO bulbs are about the same efficiency, perhaps a little less than T8 NO. With the higher wattage, you get more light in less space than T8 NO.

What sucks, yes really, really, really sucks about T5 HO is that the selection of tubes is limited and they are expensive. (Europe is way ahead of us in the regard.)

On a budget, It may be best to get a decent electronic ballast (i.e. $25.00 Workhorse ballast) and overdrive cheap T8 tubes. Lots of light for low cost, but you may fry the lamps after just 6 months. (This makes more sense to me than the tradtional T12 VHO approach now.)


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## fsnow55

*cheap T8 fixture in walmart*

Walmart sells Lights of America shoplight that can house either t12s or T8s (yes, electronic ballast) for about $8 and $14 resp. (2 models but get the cheaper one). Very cheap, 4xT8 system, for less than $50. I mounted them under a hood to replace my less efficient T12 shoplights.


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## Raul-7

Here's a chart czado (Joe) posted about the efficiency of each type of lighting. Very helpful, IMO.



Code:


bulb   Lumens/watt    Eq T12 watts
T12    58.9            1
T10    62.3            1.06
T8     91.1            1.55
T5     104             1.77
T5HO   92.6            1.57
MH     84.1            1.43
CF     79.4            1.35

HTH.


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## IUnknown

The other problem I use to have with PC is that I would always end up breaking off the end caps. They just always seemed cheaply made. I'm with gomer on the T5HO.



> Other than that I don't see that they are worth the hassle. Light is light when you are talking about a given wavelength.


I don't agree. Diffussed light gives a totally different feel than the shadow casting MH light. MH light acts like the sun, so it is more natural.


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## werner

> Now...I just noticed some very neato LED systems on the Green Chapter website, but I'll leave that discussion until they are available in the US!


These should be available Sept 4th (unless they set back the release date again) http://www.solarisled.com

Where will these fit on the best/worst lighting scale? They'd have to be significantly better than MH to justify the price.


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## gnatster

MH is more like the sun only due to the fact it is a point source bulb. The problem with MH is dispersion. The brightest light (most available lumens) is a point directly under the bulb and from there, depending on the reflector, is dispersed in a conical pyramid with a sharp cutoff at the edge.

Example Icecap 400W/250W DE Reflector

The data plots for each reflector at the distances 6", 9", and 12" are plotted as a % distribution graph to illustrate the intensity and spread at different points on the measuring grid.










From Advanced Aquarist's Online Magazine Volume V, February 2006 Product Review: Analyzing Reflectors: Part V

A straight bulb such as an HOT5 disperses the light in a more linear fashion. Picture an inverted V shape the length of the bulb. I looked for some graphs to illustrate but cannot find any.

The point is when trying to figure out what the "best" light source is the only answer is....depends.

Lets look at that a little more in depth.

What is the purpose of the tank. Are you farming plants where you want to have the best growth rates at all points? In that case a bank of straight bulbs will offer the most even dispersion over the entire footprint. HOT5's would be best in that situation.

Are you looking for a very natural look, including shimmer lines and are willing to sacrifice growing glosso or HC in the outmost corners? In that case MH would be best for the situation.

What about the overall look of the entire package? MH Tends to bulky and creates a lot of heat in one area. HOT5's can be mounted with a very shallow depth and the while the heat level for a given wattage is probably the same it is distributed over a greater area

In conclusion there is no one best type of lighting. We can discount certain types due to lack of efficiency. Spiral PC, Incandescent and most T12's fall in to this area. When it comes to where the lumens meet the water a combination of MH and HOT5's seem to offer the best of all worlds.


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