A lighting Conundrum (PC vs T5 vs T8)

[Slick Fork]

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

 

[Captain Hook]

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.

 

[happychem]

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.

 

[Slick Fork]

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!!

 

[Slick Fork]

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!