Lighting for reef-to-be

[sheamurai]

Hi
Just wanted to confirm what I've been reading against practical, 1st hand knowledge.

I've been reading that Compact Fluorescent lighting needs to be replaced every 6 months.

Is this just a marketing sell-more-lamps line, or does the light spectrum really deteriorate after 6mos as to be harmful/useless to the corals/tank?

I just bought a used Coralife fixture, and if this is the case I need to buy new bulbs for it now...

[labnjab]

If i remember correctly its every 6 to 12 months depending on how long u run them

[ILuvMyGoldBarb]

Yes, it is quite accurate. Power Compact lights, due to their design, go through a large change in their spectrum in a 6 month period and also decrease in intensity. In order to keep all that up, you need to change them out every 6-9 months.

[sheamurai]

Can you tell when they need to be changed, or do you just change them out every 9 months?
I have noticed that the actinic appears more purple than blue lately.

[kaybee]

PC's may visibily lose some of their intensity but much of what is being lost probably can't be seen by the human eye. After the 6th month mark the PAR (Photosynthetically Active/Available Radiation) of the PC's bulbs slowly diminishes and there may be a spectrum shift as far as what type of light is being produced.

When I used PC's I think I changed out the daylight bulbs 10-12 months after I got them and actinics 6-8 months after I got them.

It depends on what type of corals you have. You can run them longer if you have corals with low light requirements such as mushrooms or some LPS corals (like certain blastomussa).

In a tank with no photosynthetic life PC's can be run until they burn out or become responsible for an increase in nuisance algae (which may take advantage of the spectrum shift).

[Amazon]

i have to change mine every 6 months and you can very easily tell that the lights lose a lot of their intensity. Especially the actinics, the bulbs start to lose a lot of blue.

[sheamurai]

Hmm, ok. time to go shopping then.

There seems to be a range of opinions on lighting. From what I've read, most people seem to get actinics becuase they like the look of them. Do the corals really need actinic lighting? Would it be better for them if I got two white lights? Or two ranges of white lights?

[sheamurai]

Does anyone have a response to the above, please? Are actinics necessary for corals, or are they more decorative?

[kaybee]

Corals can utilize the type of light that actinics provide, but typically "daylight bulbs" (as a very general term) provide more PAR and cover a wider range of the spectrum.

Actinic lighting (~420-460nm) essentially is similar to the spectrum of natural sunlight that is capable of penetrating water depths of ~50ft+ in the ocean.

Actinics probably aren't "necessary" (because you can run a reef tank without them) but corals will use the energy (PAR) of the spectrum of light they they provide, so I won't say they are useless (I wonder if a T5HO actinic bulb puts out more PAR than a power compact daylight bulb of similar wattage). In that sense you can consider actinics to be supplemental lighting (which will also provide a certain 'pop' to certain corals).

What type of corals do you have and/or plan to get? For light-demanding corals that can be kept under PC's you may want to go with two daylight bulbs. For low light or moderate lighting requirements for corals that can be maintained under PC's, you could do a daylight-actinic combo.

[sheamurai]

so far all I've looked at are the "easy" corals. Zoas, frogspawn, star polyps. I would also like to keep an anemone, tho I understand that clowns won't host in anemone just becuase you have one. The bottom of the tank (to the sand) is about 17".

[Amazon]

i like one full actinic bulb. and one 50/50 daylight/actinic. it makes a cool look and yes the corals utilize this color.

[sheamurai]

does the 50/50 look bluer than straight white? Is it common to have "more" actinic than daylight?
I was thinking of changing my daylight down to 6500, as I've read that this is more optimal for photosynthesis (and algae, I understand) but I don't want to deprive my corals of better light just so I have less of an algae problem.

[kaybee]

Not utilizing 6500K bulbs isn't necessarily depriving your corals since corals can utilize the energy of the other wavelength or temperatures of light, which is proven in nature (as water depth increases more spectrums of light are filtered out). In the hobby one can achieve great growth with non-6500K bulbs.

6500K bulbs will probably emit more PAR than bulbs of identical wattage but different temperatures or wavelengths, but may not be as pleasing to the human eye (perhaps too yellow).