[art_of_war]

I got into a little discussion earlier today with someone concerning T5 vs. PC lights. Now, I went through this and I admit I lost this little argument. Clearly T5's are better lights than PCs. Unfortunately, I couldn't defend the fact that 250 watts of T5's are better than 260 watts of PCs. It has more to do with the wavelengths, lumens and penetration as opposed to wattage.

Someone help me out here. I'm right...aren't I?

[charlie]

After spending the last half hour reading about T5 vs PC, it seems that more people agree with you than not. It seems that they are equal until you start asking about the reflectors used with each bulb. When you get there, if the right reflector is used with a T5, it beats PC lite hands down.
Personally, I am a MH and VHO guy! I have seen the T5 actinic vs the PC actinic, and I personally liked the T5.
Don't know if this helps you out. Get together with your buddy and try searching that, I think you will find it interesting.

[Ninong]

Originally Posted by art_of_war

Unfortunately, I couldn't defend the fact that 250 watts of T5's are better than 260 watts of PCs.

Both compact fluorescents and HO T5 lamps are 5/8" diameter. When you use an individual reflector with each HO T5 lamp, a lot more of the light is directed downward into the tank. With compact fluorescents, a lot of the light strikes the adjacent lamp tube. Obviously there are other differences but that's a major one.

It has more to do with the wavelengths, lumens and penetration as opposed to wattage.

For starters, wattage is nothing more than a measurement of power consumption. Never assume that lamps of the same wattage, or a collection of lamps of the same wattage, are equal because that's very seldom true. This is especially true with metal halide lamps. One 175w lamp may produce three times as much PAR (photosynthetically active radiation) as another 175w lamp with a different Kelvin rating. In fluorescents, for example, an actinic lamp produces only about one-third the PAR of a 10,000K lamp even though they're both the same wattage. A 6500K lamp usually produces more PAR than a 10,000K lamp, which usually produces more PAR than a 14,000K lamp, etc. However, one manufacturer's 10,000K lamp may produce 50% more PAR than another manufacturer's 10,000K lamp of the same wattage.

Lumens is nothing more than a unit of measurement of intensity of light that is visible to the human eye. It's commonly used to rate lamps, especially fluorescent lamps, because most fluorescent lamps are manufactured for use by humans to help us see stuff. It's still a worthwhile number to have on hand when comparing lamps but PAR is a better measurement because it measures the spectral range that is important to photosynthetic creatures, such as corals, clams, etc. To put it simply, lumens is a measurement of light the way we see things and PAR is a measurement of light the way the corals see things. We're terrestrial animals, and since we haven't been nocturnal for millions of years, our vision is more sensitive to the yellow-green range of the spectrum; therefore, a lumen puts more weight on that part of the spectrum.

A comparison of PAR measurements at the same distance from various light sources is the best way to evaluate the different available light sources for reef tanks. What matters is the amount of PAR incident on the surface of the photosynthetic animal in your tank. How you get the light there is much less important. The quality of the PAR depends on the spectral distribution but then we would have to get into a discussion that would last all morning.

[charlie]

That is a good description!!!! Thanx.

Has Sanjay ever done an analysis on T5 lamps? I looked all around and couldn't find much of anything. I probably am looking in the wrong spot tho.:slap:

[Ninong]

Originally Posted by charlie

Has Sanjay ever done an analysis on T5 lamps?

Not that I know of.

I looked all around and couldn't find much of anything.

As far as I know, this site contains all of Sanjay's test results and it's all metal halides.

I have seen comparisons of various fluorescents lamps (usually in lumens) in reefkeeping articles and books in the past but nothing that I remember covering the more recent HO T5 lamps. Actually, I think I have seen stuff on T5's but I can't remember where right now.

[charlie]

Like you, I know I have seen something on the T5's, and again, I can't remember where it was.
I have Sanjay's site bookmarked, and I really thought that he had done something on T5 lighting. I wish I had asked him about them when I saw him speak in August.

[Ninong]

Originally Posted by charlie

Like you, I know I have seen something on the T5's, and again, I can't remember where it was.

We don't keep track of that stuff because we have already make up our minds concerning what is best. Even if we don't use what is "best," we know what is "best."

We know that one of these days LEDs may be "best." If you could match the intensity of 400w metal halides with lamps that last 10 years and put very little heat into the water, who wouldn't be interested. The cost is another matter. They're not there yet but they could be soon. Then people will have to consider the cost factor.

We know that corals fluoresce best under VHO actinics but we also know that VHO fluorescent lamps are a dying breed. Most combination fixtures nowadays include HO T5's with metal halides.

We know that if you stick HO T5's with individual reflectors across all of the available space above your tank, you will have enough light for just about anything provided your tank is less than 28" tall. Once you get into the 30" tall (and taller) tanks, you really should go with metal halides.

We know that the 400w Iwasaki 6500K metal halide lamps put out tons of PAR but we also know that they're butt ugly unless you add lots of actinic supplementation.

I could go on and on about what we know, but I think you get the point.

[charlie]

You bring up an interesting point about the LED's. Sooner than later, they are going to figure these lites out!!!! Right now, even Sanjay admitted that they pose a very interesting offer. (????) I think that is what he said I do remember him saying that right now, they could be compared to a 175w halide at best.
Once they get these right, who knows what we will see happen to the lighting industry. I have been tempted to try them when I redo my 300, but I have more than enuf extra lighting sitting around to justify the cost.

[Ninong]

Since the original question concerned HO T5's, here is a comparison of 4-ft HO T5's with standard output T12 fluorescent lamps that I found online.

Sunlight Supply
Tek-Light T5 High Output Fluorescent
Indoor Plant Grow Lights
These new high output fluorescent lamps have an extremely high lumen per watt rating compared to standard fluorescent bulbs, making them extremely suitable for growing and maintaining plants indoors. Each 54 watt, 48 inch long, high output fluorescent bulb produces 5000 lumens, or 92.59 lumens produced per watt of energy consumed. By comparison, a standard 40 watt, F40 cool white lamp produces a mere 1260 lumens, or 31.5 lumens per watt.

High output fluorescent lamps have a very low heat factor which allows the fixture to be hung extremely close to plant canopy, thus increasing usable light levels. The TEK-LIGHT(tm)'s exclusive 9-bend reflector is made of imported German 95% reflective aluminum to drive every available lumen of light to your plants. Light output is 300% higher in this high-tech reflector compared to cheap fluorescent fixtures.

Here.

P.S. -- Something I probably should have mentioned earlier but didn't is the fact that there is often little correlation between lumen and PAR output. This is because the narrow band response of the human eye is not the same as the response of zooxanthellae. It's true that we compare lamps, especially fluorescent lamps, in lumens but it would be much better if we could compare them based on their actual PAR output instead of their lumen output. Remember, lumens measure what we see, PAR measures what the zooxanthellae "see."

Another point to remember is that the ballasts make a difference, too, especially with metal halide lamps. With fluorescent lamps, electronic ballasts are pretty much standard now so you don't have to worry about comparing magnetic ballasts with electronic ballasts. With metal halides, there can be a huge difference between ballasts and magnetic ballasts often produce more PAR than electronic ballasts.

[charlie]

That is the link I was thinking of Ninong!!!! Thanx for the input, got that one bookmarked now too!

[Poseidon]

I have used PC's, Halides, and now T5, I can say that I like the T5 WAY better then PC, but not as much as my halides. I like the color options of T5, there are TONS of options in color, where as PC you don't have anywhere near the options. MH has the most when it comes to PAR and color options, but it also has the most heat, and the fastest power meter! My last electric bill was about $10 less then it was with Halides and VHO. I am still getting good growth, and decent color, using 320W of T5 (4 Overdriven 4 foot bulbs on an IC 660) as compared to 610W of VHO/halide.

I may add another bulb or 2, but they will be noramlly driven, and for color only.... Even then, with 6 bulbs I will be at 428W vs the 610W, not an overwhelming difference, but still a savings.

[art_of_war]

I think I may be going in the direction of T5's. My 260 watts of PC lights are just not what I'm looking for anymore. I thought I'd be happy with them but I realize it's either MHs or T5's and since it's not a huge tank and I can't really afford the electric bill, I better go with T5's.