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flourecent tubes?


johan

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Hello Reefers!

 

One day I hope to be one of you. I understood nano is not the best choice for a beginner but after two years of research I found this out: I can't afford a 200gal. Anyway, I figure I start with live rock and If I can keep that alive, I'll take it from there.

 

The actual question:

 

What about flourecent tubes? I was hopping to squeese in 6 15watt tubes in 10gal. tank. How would that compare to, for example, 2x36watt power compacts that many of you seem to be using on that size of tank?

 

By the way...

 

Why dont you mount the PC's "standing" so to fit 4 instead of 2 tubes?

 

Please don't make fun of my english skills, I'm Swedish :)

 

Thanks!

 

/Johan

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You have to be careful with fluorescents.. make sure they are of the proper color temperature and wattage (if you're going to a home improvement store, you'll likely only find 3,000K fluorescents, which aren't the proper color temps)... and don't forget about 03 Actinic fluorescent bulbs as well...

 

I can simply say from what I've read... as I have minimal experience myself... but what I found from the top_search.gif said 5 watts per gallon unless you're going with powercompacts which would be 2-3 watts per gallon.

 

Ideally you'll want the bulbs to span the length of the tank to provide full light to all areas.

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Remember that when you squeeze lights together you lose efficiency in two ways. First, less reflector surface means less light from each bulb makes it into the tank. Second, when light strikes the bulb surface from outside (i.e., from the neighboring bulbs) it actually reduces the efficiency of the bulb. An array of bulbs packed close together is probably not going to produce much more light than fewer bulbs with good reflectors, but such an array will produce more heat and use more electricity.

 

Similarly for turning PC lamps on their narrow edge: the tube on top no longer shines directly into the tank, so the only way light can get from it to the tank is via the reflector, which isn't as efficient as the direct route. Also, remember that the minimum angle for light penetrating the water surface is something like 53 degrees (or 56, I can't remember the exact angle). If light strikes the water at less of an angle than that then it will be reflected right back up.

 

So it's not really a question of how many watts of lamps you can squeeze into the hood; it's a question of how many photons you can get into the tank.

 

If you want to use NO (Normal Output) flourescents, I say go for it, but use really good reflectors and limit yourself to three tubes over a 10 gallon (the rest of the area should be taken up with reflector surface) and those tubes should be T8s. If you can get T5s, then maybe you could squeeze four in there, but I don't know of any 6500K or higher bulbs that come in 18" T5s. But because of the lower light output per watt of NOs, you'll be limited to more "deep water" corals. Still, I think it would be interesting to try.

 

Good luck!

Steve

 

P.S. Sorry for the U.S. units (gallons, inches), I don't have a conversion table handy. Let me think, 1" = 2.4 cm, so 18" = 43.2 cm. 10 gallons is about 40 liters I think. I wish the U.S. would switch completely to metric but I don't think it will happen anytime soon.

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johan,

just go T5's, i would think you could get them easier in europe via germany. you have all the spectrums and vho output but in a itty-bitty package. mighty mouse-type lighting that can still kick @ss! B)

 

i think they still spread them out (bulb to bulb) tho because it just so friggin bright!

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By way of clarification (and thanks to tinyreef for pointing this out:)), light striking the outside of the tube leads to inefficiency because it creates heat, which makes the tubes less efficient. Heat in general is a problem when you pack a lot of bulbs under a hood!

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Thanks!

 

That was very informative, in most part (J-Bass! That’s my sister you're talking about).

 

Your remarks that absorption and negative heat effect off the tubes themselves would be a factor never occurred to me and although I clearly remember being in school that day, I had forgotten all about dispersion. Still your answers raise more questions. Please bear with me.

 

Djm!

Your opinion on PC's being stronger certainly seems to be the general opinion on this and other reef boards. Still, I’m not entirely convinced that the difference would be that significant since fluorescent tubes works pretty much the same (I think) as PC’s. Can anyone confirm/deny?

 

T5 is supposedly a code for tube diameter (5/8”) and I’ve heard of T5 fluorescent tubes and I’ve seen PC’s that have been called T5 lamps. Are there both PC And fluorescent T5’s?

 

If you did a raytrace model of a reflector could you consider emitted light to be radial and perpendicular to the length of the tube?

 

And Steve!

I don’t mind the English-speaking part of the population using their own unit system. If only they could use the same (1 U.S. gallon = 0.84 imperial gallon =3.8 liters).???

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i believe some PC's are technically considered T5's (5/8") but i've always just used the term for the socket diameter area of straight tube fluorescents.

 

not all T5's are vho though whereas all PC's are vho (i believe). you could do equally well either way if you get the right spectrum and output imo. NO T5's would be a little dim for me but vho T5's output is greater than comparable sized PC's (from what i've seen in-person, haven't seen specs yet tho : ).

 

if it was me, i'd go with the T5's, no hesitation. but those !@#%$! lighting companies don't sell them here yet for the aquarium hobby (easily available setups at least).

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