T5......but Why not VHO with Individual Reflectors

[luke33]

Ok, not sure if anyone has ever discussed this before but here's my question i've been pondering for some time now. I understand the t5 is made with the individual reflector for instance the icecap makes them great especially with the overdriven IC ballast. I love my t5's....moreso than my MH's. Here's my question. Time and time again everyone is always saying the reflectors are what makes them great, and i understand why but my question is Why hasn't any company taken the vho bulb's and made a individual reflector for them? I mean a 54w 46" t5 with individual reflectors vs a 110w 48" vho with an individual reflector of the same caliber. Shouldn't the vho be superior? I understand yes the reflector would be larger and you couldn't fit as many, but the output will be twice as much, before you overdrive it. What are the thoughts on this.

Luke

[BeanAnimal]

1) the size of the reflector needed would means that you would only be able to fit a few over the tank.

2) T5s are more efficient than T12s

3) T12 bulbs are much larger diameter. That means that they cast a larger shadow under them (for the reflected light).

4) because they are larger, restrike (Light being bounced back INTO the bulb envelope) is more significant.

Hope that helps.

[BeanAnimal]

Lets do it this way:

18" tank (front to back).

You can fit 8 T5 bulbs over the tank at 54W each. That is 432W

Lets say the T12 SLR would need to be around 5 inches wide (That by most accounts is a very small estimate) You could fit only 3 of them above the tank. That is 330W

Lets just say you could fit (4) for a total of 440W.

Remember watt for watt T5 is more efficient and there is less restrike and self shadowing. So even though you have ~440W over both tanks, the T5 tank will get significantly more PAR for that wattage.

[MrZ]

The reflector would have to be much larger in order to get the same percentage of light reflected back down into the tank instead of hitting the bulb a second time - to the degree where you would only be able to get two of them over a normal size tank. You would also still be fighting the fact that T12 VHO bulbs put out significantly less lumens per watt than T5 HO bulbs.

Remember that just because a type of lamp uses twice as much electricity as another doesn't necessarily mean that it puts out twice as much light. Thats why incandescent bulbs are so innefficient - most of the electricty is used to create heat instead of light.

[pjf]

When I replaced my T12 tubes with T6 tubes, the tank received more light just because the T6 blocked less of the light bouncing off the reflector. There were no other changes. The ballasts, the fixture, and the reflectors were unchanged.

[MrZ]

Spot on as usual Bean - and quicker on the draw to boot.

[BeanAnimal]

[aaron7405]

some vho has internal 180° reflectors

[BeanAnimal]

Still nohwere near as efficient as an SLR (by a long shot)