Lighting

[TommyLiNy]

So Ive been looking into ordering light for my 55gallon. Ive been on fishneedit.com and its 98.99 shipped. My question is Home Depot sell a 48" dual T5 fixture for $35, if I can get the bulbs from my lfs wouldnt that be the same?? They sell coralife and current HO bulbs and it would save me about $25. Was thinking I could make my own fixture with the old houseing. What do you think?

 

[Crepe]

No it wouldn't work. T5 and T5HO are very different bulbs. The latter puts out tons more PAR (photosynthetically available radiation) than the former. HO bulbs do not work in a NO fixture. NO bulbs will work in an HO fixture but will not operate any more efficiently or with more PAR.

 

[TommyLiNy]

Thanks Crepe guess I'm just being cheap glade I asked. Ill going to order the T5 HO for the extra $25. Thanks for the input.

 

[BigJim]

...NO bulbs will work in an HO fixture but will not operate any more efficiently or with more PAR.

I have to disagree a bit with this statement. Putting an NO bulb in an HO fixture will overdrive the bulb, shortening its life, but putting out more light.

 

[Crepe]

I have to disagree a bit with this statement. Putting an NO bulb in an HO fixture will overdrive the bulb, shortening its life, but putting out more light.

Intensity and par aren't always correlated. Using a par meter we've found that there is no appreciable difference in PAR by over driving a T5 bulb. Also most electronic ballasts in T5HO fixtures refuse to over drive NO bulbs.

 

[BigJim]

I'll agree that most good electronic ballasts are smart enough to recognize an NO bulb and adjust accordingly.

I'm fairly new to high intensity aquarium lighting. Please enlighten me: When I was reading up on lighting for planted tanks, I found that many people use HO ballasts to overdrive their lights, mostly T8s. Why would you overdrive a light if you're not getting any real PAR benefit? I've seen both reef keepers and planted tank people do this. I went the LED route, so I didn't really dig into the fluorescent stuff.

 

[Crepe]

I would say it would be a matter of misconception and the assumption more brightness = more PAR. I'm quite positive that there are some gains in PAR by over driving, it's just that they aren't quite as apparent in T5 bulbs. There's also the fact that T5HO bulbs already put out HUGE amounts of PAR. Way more than we could possibly need in a FW aquarium and it would simply make more money sense to get the T5HO bulbs that would last upwards a year and a half than short change yourself on NO bulbs.

Perhaps the testing my LFS did was wrong...but perhaps there really is some fundamental difference between the nature of HO and NO that we don't really know about. There's also the fact most high quality T5 fixtures are going to have electronic ballasts and will not be able to over drive the bulbs so either way you're not going to see gains.

Now that I think about it...I'm almost positive our methodology is flawed while testing the bulbs. You've got me thinking....

edit: I think I'll pop a question to hoppy on TPT. He should shed some light on this situation. He's contributed vast amounts of PAR info to the hobby. Including some very interesting information on the abilities of reflectors. Regular unpolished aluminum has HUGE reflective capabilities apparently (over 50% par increase) and white paint has similar results.

 

[TommyLiNy]

See what I started lol. Look at what I thought was a simple question has led too. Id like to hear what you come up with though, not making a purchase till Thursday so anymore input would be great.

 

[TommyLiNy]

Also my lfs has the T5HO bulbs not sure if made that clear

 

[fort384]

T5 and t5ho bulbs aren't even the same lengths if I remember right. I mean you could always just change the distance of the lamp holders with a Diy fixture, but you cant buy a t5ho stock fixture and put a standard t5 bulb in it without some modification.

The other important factor here are the reflectors. They make a huge difference. Any t5ho fixture worth its salt will have individual highly polished reflectors. Stock t5 fixtures from your LHS will most likely have junk reflectors in comparison (at least for aquarium lighting application). I read that the PAR of a t5ho is cut in half if a single reflector is used for multiple bulbs, vs. an individual reflector for each bulb. Will post a link if I can find where I read that...

 

[Crepe]

One theory seems to be a shift towards a blue color in over driven bulbs. Great for reefs which like blue light a lot but tough on plants since the red wavelength has been distorted.
edit: The plot thickens...contrarily Hoppy has mentioned that color spectrum shouldn't shift in over driven bulbs...I'm starting to think that the mistake was made in the ballast of the fixture...on our behalf.

 

[BigJim]

Sorry to cause trouble, but I'm interested to see where this goes.