<a href=showthread.php?s=&postid=15449938#post15449938 target=_blank>Originally posted</a> by ulysses191
I guess I'm trying to figure out what would be comparable in wattage between VHO's and T5's.
So, a single 48" 54w T5 outputs as much or more par
as a 72" 160w VHO?
I prefer my lighting to have a crisp white on the blue side, but not really "blue".
I don't think I really need more PAR with the reeflux and lumen brights.
If I like the reeflux bulbs on their own, I would use the flourescents for dawn/dusk.
Would a pair of the 48" 54w t5's be enough for that application?
Sorry if this is confusing.
It's the reflectors ... T5 and T12 VHO is similiar enough in par, watt for watt but T5's small diameter allows for individual reflectors to be clipped onto each lamp which reflects nearly all the light emitted from the lamp, down into the tank where it counts. The downside is that they need fan cooling to optimize the output and to get a long usable life out of the T5 lamps. The small diameter means less surface area to dissipate heat.
So ... With T5 you need an individual reflector for each lamp (they just clip on the lamp) and good fan cooling. I would run the lamps the full of the tank so that your color supplementation is uniform thoughout the tank. The same length T5 versus T12 VHO is still lower wattage by a good margin, about 1/2. But, It shouldnt be about using as little wattage T5 as possible to equal the output of VHO. Taking that approach in order to use shorter lamps will just give you non-uniform cover supplementation.
Properly cooled, the T5 lamps can have an effective life of over a year for the blue lamps and 18 months for the whiter lamps. This is based on using them for a regular, daily photoperiod ... 10 to 12 hours per day (their effective lifespan is actually stated in hours). Obviously, if using them only for part of the day as supplements for the halides, they can will longer as would the T12 VHO in the same application.
I ran T12 VHO for over a dozen years as my main lighting. I replaced at 6 - 7 months. At that replacement schedule, there was a very signigant visual differrence both in terms of output and color between the old lamps and new lamps.
With T5, comparing a new lamp with an old at 12 months, visually I see a much smaller difference in color and output between the new lamps and the old lamps. And this is with the blue/actinic T5's being overdriven by an Icecap ballast which shortens their life compared to the standard high output ballast driving them at the stated wattage.
Bottom line is that T5 lamps are supposed to have a longer effective usable life than T12 VHO and they do.
The only reason why I personally would run T12 VHO over T5 for supplemental halide lighting is if I were to run the T12 VHO super actinic, 420 nm lamps. The color of these particular spectrum lamps is superior with the T12 VHO lamps over the T5's.
Aside from that, T5 has the advantage in output into the tank with and because of the external reflectors and they do so with less wattage which means less heat and less energy used. The ballasts are also generally less expensive. $50 - $60 for an Advance brand T5 ballast that will run 4 X four foot T5's for example. T12 VHO are usually run with Icecap ballasts ... the Icecap 660 will run up to 16 feet of T12 VHO lamps with a maximum of 4 lamps and they cost in the 150 dollar range. These ballasts will also run the same number and length of T5 lamps and will overdrive most of them for even more output (for example, they will drive a 54 watt T5 at 80 watts).
T5's do have a longer usable life which means they are more economical to replace and and there are a few more colors available. But they need to be fan cooled in order to perform at maximum output and to get the long lifespan. And again, you need to purchase external reflector for each lamp in order to reap the signifigant output advantage. The external reflectors are generally 2" - 3" wide depending on brand and they are a one time purchase and cost maybe 22 dollars, give or take for a reputable brand, popular 4 foot reflector. A little more for the longer ones and less for the shorter ones.
Cant think of much else off the top of my head but Im sure others will chime in and this will turn into an interesting debate
