Convert Power Compact to T5's?

[conjuay]

This question came up in our local forum, and I thought I would ask it here as well:

Would the ballast that fires 2X65 power compacts be used to fire 2X54 T5's?

Would it be an slightly overdriven T5?

Or, to ask the same question a different way, can a PC fixture be retrofitted to T5 by just changing and rewiring end caps?
Thanks

[BeanAnimal]

It really depends on the actual ballast. Some will fire the bulbs and some will not. However, unless you replace the crumm PC reflector with good SLRs for the T5s, you gain no real benefit :)

[troylee]

on that note bean if you retrofit the pc's with ind. reflectors like the t5's will they perform as good????? i know t5's are only good because of them and a pc is a t5 wrapped around it self.......im curious myself on this i have alot of pc's and a full blown fab shop were i can make the reflector's...

[BeanAnimal]

No, you will not get much benefit at all. 1/3 of the light from a PC shines into itself and is scattered/absorbed as heat. The SLR works because it directs light from the top 3/4 of the bulb into the tank very efficiently. There is no way to fit such a reflector to a PC bulb due to its shape.

[One Dumm Hikk]

Bean, is there an easy to way to find out if a ballast will fire T5s short of wiring it up and trying it? I have an 8x65W PC fixture that was given to me and I kept it in the hopes of doing this very thing and using the ballasts on T5 bulbs.

[BeanAnimal]

I am not sure I am well versed enough on the different topologies to answer that question with complete confidence. PaulErik is the resident ballast expert. In theory the ballast will fire the bulbs, but I am not sure about current limiting. That depends a lot on the ballast technology employed.

[troylee]

lol bean there is no way huh????? im gonna have to see that for myself....i have already thought about it.....it can be done im not sure if it will work being like you said it shine's on it's self... i could get a reflector in between those 2 bulbs but it would be so close.... i think it would probally take away some light if anything.......but saying that it does shine on it's self would'nt that just give the bulb more intensity???? i could google these ????'s but i would be on here all night and i know you got the answer's thanks bean.......

[One Dumm Hikk]

troylee, trying to fit a properly sized parabolic reflector on a PC bulb won't help the bulb. The reflector would be so close to the bulb that it would simply reflect the light back into the bulb. Then you are simply reflecting it back into two legs of the bulb instead of the bulbs simply shinging into the other leg.

[One Dumm Hikk]

Thanks Bean. I am going to get the light fixture this weekend (its at a friends house) and get the ballasts where I can see them and then I can start asking specific questions about them.

[BeanAnimal]

The shape of the reflector and its distance from the bulb are critical in determining the lights path and how much of it makes it to the water. Any time light strikes an object, some of it is absorbed as heat and some of it is scattered (goes in a direction that you do not want it to go).

The tube shining on its other half does not make the light more intense, it simply scatters a significant portion of it and turns some of it to heat.

Sure you can stuff reflective material between the bulbs, but to what benefit :)

[troylee]

that's what i was asking if it did.......make's sense..... thank you!!! i have 2 jbj 65w x4 fixtures i was gonna strip to supplement my mh's.......they come with a single reflector over all 4 bulb's.......ok so i was gonna make new ind. reflector's for all 8 lamp's what would be the idea distance all the away around the bulb's???sorry for getting a little off subject on this thread i was gonna use a pm. but figured this might help other's in this situation........

[BeanAnimal]

The SLR reflectors for T5s come with clips that set the bulb at the proper distance.

[sploke]

So, you can't use fixed endcaps with those reflectors if they are not at the exact height as the clips? Do they make pigtailed T5 endcaps? All the ones I've seen have been fixed.

[NanoReefWanabe]

my PC ballast will fire t5 bulbs...is says right on the ballast...but i dont think it will fire HOt5's