When they say X watts per gallon...

[JHawlz9989]

When they say a tank needs around X watts per gallon of lighting, does that refer just to how much actinic you need, or a mix of actinic and daylight?

Josh

[deangelr]

Watts per gallon is a term that isnt all that applicable for reefkeeping today.

what kind of lighting do you have? what is your question?

[bertoni]

Watts per gallon isn't a very useful metric because some lighting setups are a lot more efficient than others. Once you've decided what animals you'd like to keep, we can hep more. Generally, actinic bulbs seem to be less efficient, for example.

[wmdick_2007]

It is a good reference that most understand. If you know you have good bulbs, the right three wavelengths, etc,. it is a good scale for judgement. It is not just how much light, it is at what depth this species is usually found and do I have the required lighting to keep it alive and hopefully growing.

"This applies to aquariums when we consider the light spectrum and how it applies to our aquariums individual needs: Red light is the first to be filtered out and can only penetrate a short distance. As light waves penetrate deeper into the water, orange and yellow are lost next. Of all the colors of the spectrum blue light penetrates the deepest. Corals need intense equatorial UVA (actinic). Most higher plants need a balanced PAR light range (see section about PAR).
The Nanometer scale and Kelvin temperatures come together when applied to aquarium lighting this way; Natural sunlight on a clear day registers at 5500- 6500 Kelvin degrees. Kelvin temperatures less than 5500K become more red and yellow and the higher the Kelvin temperature the more blue the light is.

Most photosynthetic invertebrates should be kept with lamps of a daylight Kelvin temperature from 6400-14,000 K (higher Kelvin with deeper specimen placement, not necessarily tank depth). 20,000K daylight lamps can also be used for deeper tanks, however these often have poor PAR and it is better to use a 14,000K Daylight or less supplemented with more blue.
Photosynthetic invertebrates (many corals, anemones, clams, nudibranch, etc.) also need more blue (400-550nm) than "higher" plants, with 465-485 recently being shown the optimum blue. Not only is blue/actinic lighting beneficial to photosynthetic invertebrates, it is also aesthetically pleasing to the eye when used to supplement "daylight" lighting. "

From here : http://www.americanaquariumproducts...._Lighting.html

Clean water ---> fine filter and carbon helps light penetration !

[bertoni]

Well, actinic bulbs are deep blue, not particularly strong in the UVA range. Corals don't seem to need "intense UVA", for whatever is meant. They often show the best growth at comparatively low Kelvin ratings, like 6800 or so. Most photosynthetic organisms have the ability to use a wide range of frequencies for photosynthesis, via various compounds that absorb light. The Kelvin scale doesn't mean much beyond 11,000 or so, and the bulb rating are fairly arbitrary at that range.

A factor of 3-4 or so might be typical as a difference between a high efficiency setup and one that's not. There's various lighting data that Sanjay Joshi and others gathered, if anyone wants to do a lot of reading.

[JHawlz9989]

Well right now I have 30W of 10,000K daylight and 30W of actinic. All are 18" Coralife flourescent bulbs. From what I've read the PAR is what's really important as a measure of how much light plants are getting, but watts are a good way to indirectly determine how much PAR you have.

deangelr, I didn't have a specific question per se, but when I hear people refer to watts per gallon, I had never heard them say if this light is all actinic, or a blend. Actually, I guess that would be my specific question.

bertoni, I would love to do a lot of reading. Any specific links or literature?

Josh

[bertoni]

This page has a lot of data on MH:

http://www.manhattanreefs.com/lighting

There's some data on T5 around, but you'll need to ask in the equipment forum, I think.

The major components of a lighting system are the bulbs, ballasts, and reflectors, and all three need to be good quality for the most efficient results. In your setup, efficiency is less important (and likely harder to achieve) because of the small size.

[Wolverine]

One of the many problems with the watts/g rule is that it ignores differences in tank shape. A 40g high will need very different lighting to properly light corals near the bottom of the tank than a 40g long will, as an easy quick example. Both would calculate the same on W/g.

[wmdick_2007]

Regular T-5's are not much better than Normal Output Fluorescent tubes. T-5 HO is better and SHO -- T-2's worth upgrading to. MH for Coral needs.

About 25% of effective is lost in the first cm of water ---> 2.54 cm per inch. A 400w MH is about 140-watts effective ---> reflector, height above water, surface turbulence, all play a role.

i doubt there is an upper limit to tank lighting with current technology. However, IMHO species selection and/or placement is critical.

[iamwrasseman]

Josh ,its a pretty obscure statment "watts per gallon" and it all has to do with the depth of your tank the deeper the more watts but it really doesnt have anything to do with watts per gallon as your looking for par readings at certain depth .