Lighting Help

[OrchidForumGuy]

Hi all,

I have an 18" x 18" x 24" enclosure and need some help with finding the best lighting option, preferably LED. I had a small LED fixture, but after buying a lumen meter, it is no where near strong enough. It's a 12W, 6500K Fluval Aquasky, and the lumen reading at the bottom of the enclosure reads at 400, and fairly close to the top reads around 3000 lumens, which comes out to 279 FC.

Any recommendations?

[Roberta]

Getting useful information from a meter is challenge. Simple test is to put your hand in the plane of the leaves, with a white sheet of paper under it. If the shadow is sharp, it's good for high-light plants. If the shadow is fuzzy, lower light plants such as Oncidiums. If little or no shadow, then low light plants such as Paphs and Phals. Duration is also a factor - 12 hours a day is a good goal for plants with origin near the equator. And if there is also light coming in the window, so your artificial light is a supplement rather than doing the whole job, even better.

Sometimes low-tech can give you more useful solutions than depending on tech that isn't necessarily answering the right questions.

[estación seca]

Most aquarium lights are not designed for growing plants. Many aquatic plants do fine on extremely low light levels. Water rapidly attenuates sunshine, yet some commonly used aquarium plants survive many feet below the surface. They grow faster in planted tanks with extra light and carbon dioxide, but that's not natural.

I went to the Fluval Web site for your fixture and saw this:
"Ideal for freshwater and FISH-ONLY marine aquariums"

So it's not intended to be bright enough for coral, nor high-light plants. Or perhaps the spectrum emitted isn't proper for coral.

I wonder whether your light meter is accurate.

In a small enclosure like that, any fixture supplying wavelengths the plants can use should work OK to start. I would put that fixture on the tank and try a few sturdy plants. You can observe how they do and draw conclusions.

Edit: LED lights like this tend to have green, blue and red emitters whose output when combined makes human eyes think it's white light. If the wavelengths emitted by the LEDs can be used for photosynthesis by plants, the plants grow. If not, the plant won't get enough light. So you can't decide whether an LED fixture is good for plants by looking at the color of the light emitted.

[Dimples]

Lumens are a unit for measuring how bright a light looks to the human eye and are not a good measurement for determining if a light will grow plants successfully. A bulb with high lumens will look bright to us but could be extremely weak from a plant’s perspective due to the wavelengths it is emitting. Some grow lights look very weak to our eyes but give plants exactly what they need to grow well. This isn’t the case of brighter = better.

If you’re supplementing natural light, almost any LED grow light will work so long as it’s not too weak for the setup.

I’m using the GE 32w grow bulb about 3’ above a small table of plants. It’s almost too much for my jewel orchids and a phal and some small alocasia are growing happily.

[Steve83]

12w is enough for most plants at the distances with that tank, since you don't have to penetrate water...

Estacion, I have to wholeheartedly disagree with the overly-broad statements of aquarium lighting. The various disciplines involving aquariums be they freshwater or reef, are light years ahead of the orchid community in terms of lighting knowledge.

What the labeling on that specific Fluval light means, is that the spectrum isn't ideal for inverts or various types of corals, be they sps or lps. It has nothing to do with wattage/power.

OP, what do you plan on growing on the tank? Thats where you should start.

[OrchidForumGuy]

Thank you all for this information! I especially value the information that lumens measure how bright a light is from human eyes, that really changed everything!

---------- Post added at 08:55 AM ---------- Previous post was at 08:51 AM ----------

Originally Posted by Steve83

12w is enough for most plants at the distances with that tank, since you don't have to penetrate water...

Estacion, I have to wholeheartedly disagree with the overly-broad statements of aquarium lighting. The various disciplines involving aquariums be they freshwater or reef, are light years ahead of the orchid community in terms of lighting knowledge.

What the labeling on that specific Fluval light means, is that the spectrum isn't ideal for inverts or various types of corals, be they sps or lps. It has nothing to do with wattage/power.

OP, what do you plan on growing on the tank? Thats where you should start.

To answer your question, I'm growing mostly Paphs, and have several Dendrobium moniliforme that are mounted and hanging closer to the lights. Everything looks nice and healthy, so I assumed that the lights were sufficient, but I just wanted to make sure. My room has no windows whatsoever, so I need lighting until I move out at the end of the month where I'll hopefully have enough natural sunlight coming in to the room.

[estación seca]

Originally Posted by Steve83

Estacion, I have to wholeheartedly disagree with the overly-broad statements of aquarium lighting. The various disciplines involving aquariums be they freshwater or reef, are light years ahead of the orchid community in terms of lighting knowledge.

What the labeling on that specific Fluval light means, is that the spectrum isn't ideal for inverts or various types of corals, be they sps or lps. It has nothing to do with wattage/power.

I'm unclear what you mean. I wrote.

So it's not intended to be bright enough for coral, nor high-light plants. Or perhaps the spectrum emitted isn't proper for coral.

Isn't that approximately what you wrote? The label doesn't specify why it's not intended for coral. That would mean either it's not bright enough, or it's the wrong spectrum.

[Steve83]

Originally Posted by estación seca

I'm unclear what you mean. I wrote.

Isn't that approximately what you wrote? The label doesn't specify why it's not intended for coral. That would mean either it's not bright enough, or it's the wrong spectrum.

I agree on the spectrum part, but 'not bright enough' (I assume you mean lacking in power), isn't a safe assumption to make.

---------- Post added at 08:23 AM ---------- Previous post was at 08:21 AM ----------

And 6500k is a great spectrum for growing, and viewing, plants.

[Dimples]

Originally Posted by Steve83

And 6500k is a great spectrum for growing, and viewing, plants.

A LED light will a color value of 6500K can be generating light wavelengths that aren’t very useful for photosynthesis, or it can be great for plants. Older light tech could rely on the kelvin value to determine if the light spectrum was suitable for plants but some LEDs use films to change the final color of the light we see. Unless the LED diodes are fully exposed there could be a color correcting film included that the user is unaware of. I’d expect the use of films is mostly found in lights that aren’t intended to be used for plants, but that’s a guess.

[estación seca]

Color temperature in degrees Kelvin has zero bearing on whether a lamp will work well for plants. Color temperature is a measurement of how the light looks to a human eye, not to a plant. Color temperature conveys no information about what wavelengths are in the light. When people are shopping for plant lights they should completely ignore color temperature, except to inform them about how it will look to their eyes. It is a random accident old fluorescent tubes with a color temperature of 6500K were good for plants.

I have had aquariums on and off since the mid 1960s, starting with incandescent and natural lighting through windows. It is certainly true modern knowledge about lighting for saltwater aquaria and corals is far advanced compared to a few decades ago.

I was contemplating a densely planted tank not long ago, and read extensively about lighting. Over and over again people much more knowledgeable than I said most LED lights intended for salt-water reef aquaria, though very bright, did not provide light in wavelengths suitable for freshwater aquarium plants. They said it was necessary to investigate the wavelengths emitted to ensure the lamp would be good for plants.

Because our eye thinks light is white does not mean there will be photons in the light suitable for our plants.