Basic Lighting questions

[tasha369]

We have a 75g 18"h FOWLR and also want to have some low light mushrooms, anenomies, etc.
1) The Kalvin value is basically on for looks right?
2) The lighting different species need is the intensity which is the watts not the K value, right?
3) Does anyone have an opinion on 48" Triton triphosphor light?

[Ninong]

Hi tasha369, welcome to Reefland!

We have a 75g 18"h FOWLR and also want to have some low light mushrooms, anenomies, etc.

Mushrooms are low light, anemones require moderate/high light.

1) The Kalvin value is basically on for looks right?

No. Kelvin is a temperature scale. The Kelvin value is supposed to be an indication of the color temperature of a lamp relative to a radiating black body. However, Kelvin values used by lamp manufacturers frequently have more of a relationship to marketing than to anything else.

2) The lighting different species need is the intensity which is the watts not the K value, right?

No. Watts is an indication of power consumption, nothing else. PAR (photosynthetically active radiation) is an indication of the quality and quantity of the light. Irradiance is an indication of intensity and it is easily, if imperfectly, measured by an inexpensive luxmeter. Obviously a PAR meter would be better but they are more expensive.

3) Does anyone have an opinion on 48" Triton triphosphor light?

I have no experience with that particular lamp.

[tasha369]

Hi tasha369, welcome to Reefland!

Mushrooms are low light, anemones require moderate/high light.

No. Kelvin is a temperature scale. The Kelvin value is supposed to be an indication of the color temperature of a lamp relative to a radiating black body. However, Kelvin values used by lamp manufacturers frequently have more of a relationship to marketing than to anything else.

No. Watts is an indication of power consumption, nothing else. PAR (photosynthetically active radiation) is an indication of the quality and quantity of the light. Irradiance is an indication of intensity and it is easily, if imperfectly, measured by an inexpensive luxmeter. Obviously a PAR meter would be better but they are more expensive.

I have no experience with that particular lamp.

Everyone says 2-5 watts per gallon for reef tanks. I mostly want fish only and a few invertabrates and low light other stuff. Then everyone talks about using 10,000k or higher in the bulb so they get a better look. Why would I want a higher K value bulb? How many watts per gallon is considered low light 2watts per gallon?

[Ninong]

Everyone says 2-5 watts per gallon for reef tanks.

The only people that I know of who still talk in terms of watts per gallon are uninformed LFS employees whose advice is frequently inappropriate and often totally wrong.

I mostly want fish only and a few invertabrates and low light other stuff.

For your stated purposes, four 40w normal output fluorescent lamps would be adequate. That would be more than enough light for mushrooms and most soft corals.

Then everyone talks about using 10,000k or higher in the bulb so they get a better look. Why would I want a higher K value bulb?

This is mostly a matter of personal preference. Sunlight is approximately 6000K but most people prefer the appearance of 10,000K lamps, which mimic light several feet below the surface. If you are using fluorescent lamps, I prefer a combination that is half 10,000K and half actinic.

How many watts per gallon is considered low light 2watts per gallon?

Watts per gallon is a measurement of power consumption and has no real bearing on anything. If I place a single 250w 10,000K HQI DE lamp over a 20-gal tank, I will have 12.5 watts/gallon. If I place the same lamp over the center of a 100 gallon tank, I will have 2.5 watts/gallon. A clam or an SPS coral that is positioned exactly the same distance beneath the lamp in either tank will receive exactly the same irradiance and will thrive just as well under 2.5 watts/gallon as it will under 12.5 watts/gallon.

The only thing that matters is the quantity and quality of the light incident on the suface of the animal, not how much water volume the tank holds. Another reason that watts/gallon is totally misleading is that some metal halide lamps put out three times as much PAR as other metal halide lamps of the same wattage -- 175w Ushio 10,000K lamps put out more than three times as much PAR as 175w 5500K Venture lamps. Not all lamps of the same wattage are created equal. Another example of that is the fact that my 250w 10,000K HQI DE lamps put out more PAR than almost all 400w metal halide lamps with the exception of the 400w Iwasaki 6500K lamps.

Here is another example of the futility of the so-called watts per gallon rule of thumb based on fluorescent lamps: True 6500K fluorescent lamps put out more lumens than true 10,000K fluorescent lamps and they put out more than double the lumens produced by actinic fluorescent lamps -- fluorescent lamps are usually rated in lumens because they were originally intended for human visual needs.

The so-called watts per gallon rule of thumb is totally misleading and always has been. It was promulgated by hobby authors who were creatively-challenged.

[Poseidon]

It never ceases to amaze me how often that Watts per gallon thing comes up. No harm meant to you Tasha, you were told that figure from what you believed to be an informed source. I think Ninong gave the best example of why that "rule" is such rubish.

For Mushrooms a nice PC fixture, a couple of VHO's 1 white 1 blue, or 4 Normal Output bulbs, 2 white 10K 1 50/50 1 Blue would look nice and meet your needs.