light change idea

[segraves1]

In my 100gal (W48" X D24" X H20"), I have a pair of 400W 6500K Iwaskis and 4 65W 7100K PCs.


With my algae issue, people were talking about light and all kinds of things, but it made me start thinking about how I'm running my lights. I have up to this point been running all of these lights for 13-14 hours a day but it has been brought to my attention that really the main point of the halides should be to recreat the mid day "high light" time.

With this in mind, I am THINKING of adding another set of 65W PCs but having them be 50/50s and running these for the 13-14 hours a day. This way I save my 7100Ks and Halides for that "high light" time and not only have them last longer but better recreat the cycle of daylight.

Sound like a good idea or no?

[dakar]

Tanks with halides we run for 8 hour daylight cycles, with actinics coming on an hour before the halides come up and going off an hour after they go down.

PC's we generally run 11-12 hour photoperiods. I haven't really done enough experimenting with PC's to determine what is more damaging, long run times or number of starts. However fans to dissipate the tremendous heat developed at the end cap end will help improve their rather short lifespan. (best we've gotten is ~ 8 months)

I've found that the length of time a halide runs has very little effect on its life expectancy; instead the number of times it's actually fired will have a more dramtic effect. The 'probe start' is just that, there is a probe to start the arc through the envelope to start the light output, each time it's fired a bit of the material it's made from is expended, until it's too short to effectively start the from end to end.. The resulting grey to black coloring beginning at the ends of the inner envelope is what remains of the probe.

[segraves1]

Well what I'm trying to pull off is a setup where I can have "light" over the tank for 13-14 hours so I can WATCH the fish but don't want to run my "main" lights for that long. I could almost use a "shop light" but I'm sure the very red wavelength would cause all kinds of issues with algae growth.

[lReef lKeeper]

i think the pc's being on for that amount of time would be ok. mine have been running for 12 hours a day every since i got them ... almost 8 months ago. of course mine are on a 125 (6' tank), but that really shouldn't have much of an effect on them.

[segraves1]

I've found that the length of time a halide runs has very little effect on its life expectancy; instead the number of times it's actually fired will have a more dramtic effect.

I have been thinking about this statement this afternoon and have another question.

How is it possible that "run time" is less of an issue than the number of "starts"? As I understand it, after about a year or so, the light output shifts towards the red zone and requires bulb replacement. It would seem to me that the more TIME the bulb is ON, the sooner the "red shift" will hit. Correct?

[dakar]

That has not been the case in my tests, granted they were mostly subjective as I don't have access to all the fancy big dollar toys (yet). I set a halide on a timer so that it would fire and run for an hour, then shut down and cool for an hour, then fire again. In 3 weeks the inner envelope was almost black and the bulbs output had shifted so far it you'd think it was a headlamp from the 50's. The cathode/anode were pretty much burnt away to nothing, and within days of that it wouldn't even ignite any more.

[segraves1]

I understand what you are saying. Your study is 100% about "life" of the bulb (as in will it even turn on) vs. I was asking more about the "color life" of the bulb (how long before the color shifts and is nolonger of any use to me).

[dakar]

Ah... gotcha, wish I had a spectrometer... maybe one of these days I'll stumble across one.... then the fun will really begin!

[dsfdbutterfly]

Chris,

This is not from the perspective of bulb life or anything else. You may very well be sitting in front of your tank for that many hours. That's why you want your tank lite for so long. Most of us are not. I once came across an article that helped me with my lighting though. The wonderful thing about timers and tanks in our homes is we can "set" when we want the sun to rise and fall. If your an early riser and spend most of your morning in front of your tank then you can set your timers to reflect this. If you like to stare at your tank at night then set the timers to stay on longer for when you get home.

There is nothing that says you have to stay with a noon time rise and fall. As long as the tank isn't in a room that will be naturally lite by the sun then you can determine the lighting cycle. Therefore you don't have to have an unnaturally long lighting cycle of 13-14 hours. You can even bump the weekend hours up to match your schedule as long as your not throwing it off by too much. The sun never rises and falls at the same time naturally.

This is just something to consider. I also have MH lights. I had to add additional lights so that I could accomplish what I wanted. My MH are on for 6 hours a day. The PC lights fill in the gaps and the actinics come on in the morning and fade out the day. My lights are on for a total of 12 hours. Actinics make up an hour 1/2 of that alone. PC's are on the other 5.

I don't know if this helps you at all. Just what I ended up doing for my tank.

Angie

[segraves1]

I'm not exactly "sitting in front of" the tank for 13-14 hours but my parents are up and working by 6 in the morning (work from home) and then I don't usually get home from school till late afternoon so I watch the tank at night. In order to work for everyone, the tank needs to be "lit" from about 7AM-10PM so I'm trying to come up with a "low light" kind of setup that we can all "watch the stuff" when outside of the "noon day sun" of the halides.