T5 light setup, and color filters

[wkjames]

I am working on the T5 light setup and I have a question... 10000k bulbs go for between $15 for cheapies to $25 for higher end bulbs. 5000k bulbs can be purchased for $8. Has anyone ever tried tube filters for boosting the color temp up? http://www.rosco.com/us/filters/fluorescentSleeves.asp Deep in the PDF documents they mention filters that can bring the color all the way from 2800k to 10,000k. Apparently its possible. How might this work for reefkeeping? It certainly seems like it might keep costs down, esp. over time.
Thoughts please? (experience would be better)

[hypertech]

I'm just getting into fish, but I know a little bit about light filters and might be able to help here.

Filters are passive meaning that they just block the parts of the spectrum you aren't interested in. They can't add anything that wasn't there to start with.

So, could you put a filter on a 5k bulb and get 10k output - probably YES, but only if there is energy in the spectrum there and what you would get would be MUCH less intense than a 10k bulb.

I'm assuming that there is a difference in the gas composition between a 5k and a 10k bulb such that the 10k bulb puts out a lot more energy in that region than the 5k does.

[wkjames]

I guess I presumed the difference was more related to the coating in the bulb. I have no idea really.

[hypertech]

It could be, but it wouldn't make much difference.

If there is a coating on there making it 5k, you still aren't going to be able to get the 10k energy unless you could get the other coating off.

I'm basing my comments off of some experience with theater lighting gels (similar to the filters you linked to) and extensive knowledge of electronic filters. There is a small possibility that I am completely wrong and something like that would work, but I doubt it.

It sure would be nice if it were that easy.

[David Grigor]

Hypertech is correct. The phosphors in the bulb are different to produce the different specturms. Not just a coating on a bulb.

This has been talked about for years with MH, same principle would go for T5s. Any filter is going to reduce intensity so it may be possible but you will end up with less light as a result. In return, would need more bulbs and more wattage to compensate for the losses.

Net result: Fork out the $10 more for a good quality higher K bulb if that's what you intend to run.