A lighting Conundrum (PC vs T5 vs T8)

S

Slick Fork

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Dec 27, 2005
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Wild Rose Country
Hi there,

I'm in the process of planning and building my own canopy (so much for the "this one will do for a year or so sentiment!!) My conundrum is this, I'm shooting for about 2 WPG in my 33 Gallon tank (36"X12"x16") I checked out some CF setups and in that area I could go with either:
1 65w CF fixture---about $130 CAD+tax
2 32w CF lights----About $190 CAD+tax
Anything in the 36" range is about 96w and as this is my first planted tank I do NOT want to break the 2.5wpg barrier and have to add a CO2 system (small steps!!) I don't mind adding excel, but co2 is something I can wait to fool around with after I've played for a while.

My problem with the 65w is that the bulb is only 21" long, leaving 15" of my tank without direct light over top. The reflector it comes with is 30" but I don't know how effective that 9 extra inches of reflector will be with no light underneath it.

The 2 32w bulbs would be an ideal solution as they are 15" each, give me the right amount of light and just about the right amount of coverage. Only trouble is I don't know if I can justify the extra $60 right now and one of the bulbs is actinic meaning I've gotta fork over another handfull of dollars for a daylight bulb.

My third choice would be a 36" T5 Double strip light. This would give me my full 36" of coverage but at 21W per bulb that only gives me 42W total which puts me at a meager 1.4WPG (I thought I read somewhere that 1 Watt of t5 is like 4 or 5 Watts of t12, any thoughts). However, this one is the easiest on the old pocket book coming in at $89CAD+tax

My last choice would be to see if I can find a 36" shoplight to mount in the canopy and throw some t8 bulbs in there. However when I start breaking down the available front to back depth in my planned canopy I start to wonder if maybe a shoplight would be much too bulky.

I would really appreciate any suggestions you guys could help me out with. I've got a similar thread going in the DIY forum I know but I don't seem to be getting many views let alone replies on it so I thought I would try my luck up here.

Thanks in advance for all the replies!

Cheers
 
The watts per gallon guidelines are based on T12 fluorescents I believe. So anything else will be more intense. T5>T8>T12

I'm not going to try to guess how much of a difference between each, but I know the above is true. Power compact bulbs are basically T5s I think, so they are definitely more intense than T12s. Reflectors are also a big factor here. A good reflector will make a big difference.

If I had to guess, I'd say 1.4 wpg of T5 light would be around 2-2.5 wpg of T12.

I don't recommend the 65 watt because of the coverage issue you mentioned. Shoplights are good for $ savings but a lot of the time they can't take T8 bulbs.

Hope that helps a bit.
 
Although I wouldn't care to wager just how much more light a T5 produces than a T12, I would have a hard time believing that it is as much as 4-5 times. My rule of thumb for these is to start by comparing the bulbs to a T12 of equal length, then rounding up in terms of wpg.

In this case, 2x3 ft. T5 I would start by thinking 2x3 ft. T12, which are each 30 w, so you're already very close to your 2 wpg goal with about 1.8 wpg. Given that T5's produce more light, we can assume that this T5 fixture would put you pretty much in the ballpark you're seeking. So I think that your best option is to go with the T5 fixture and spend some of that saved money on a reflector for it.
 
Thanks for the replies, The more I think about it, the more i'm liking the t5 idea. I can go with a lower profile hood with this lamp as well (not a huge fan of canopies that are as big as the tank. Keep the thoughts coming!!
 
On the way back from work today, picked up the coralife 36" t5 double strip fixture and what a difference it made. I know that the visible spectrum doesn't necessarily reflect what the plants can make use of, but it LOOKS about 6 times brighter than the crappy 20w 24" bulb that came with the kit!! Plants seem to almost instantly look better as well!
 
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