With this post I wish to relate my experiences with the use of an alternative lighting fixture* for a planted aquarium—a T5 striplight designed for indoor gardening. I purchased this light for substantially less than the cost of most comparable 48″ aquarium lights, although there are a few important distinguishing features worth noting. For one, the fixture amounted to a power cord with switch, a polished aluminum reflector and a simple long rectangular enclosure holding the lamp end caps & electronic ballast. It lacked the sturdier housing and plastic lens built into most aquarium fixtures.
It came supplied with a single 48″, 6400K, 54-watt, HO T5 lamp. The manufacturer also offers a similar model in a 24″ length with a 24-watt lamp.
T5 Light Fixture
When I saw this light in the store—Paradigm Gardens (external link) a local garden center specializing in progressive gardening supplies—I immediately thought that it would compliment the “raw industrial” style aquarium stands that I have been building. The next picture shows the light installed over the tank where I am using it, a 55 gallon riparium featuring Cryptocoryne species plants, ferns and Anubias.
Cryptocoryne Riparium 3-VI-09
I resolved a few important details of how to set up the light in this manner.
I used several feet of light jack link chain along with a few other pieces of hardware to hang the fixture. The next picture shows the S-hook, eye bolt, fender washer and toggle assembly that suspended the chain from the gypsum ceiling. The washer covered the large hole that I drilled for passage of the spring toggle.
Eye Bolt Assembly
The next feature served as a convenient height adjustment device. This little steel hook held the chain with one clasped end.
T5 Light Hanging Assembly
To adjust height, the open end of the hook was simply passed through a link higher up the chain. This was handy for servicing the tank and for modifying the intensity of light shining on the plants. While working in my displays, I have found this arrangement highly preferable to sliding strip light fixtures about on top of the tank: I can open the top of the tank entirely, while not having to worry about a dangerous slip of the light into the aquarium water.
T5 Light Hanging Assembly
This fixture was so light in weight that it has a tendency to hang crooked, the weight of the grounded power cord pulled it away from square. To correct this problem I used a sticky-back hook & loop fastener (arrow) to steady the power cord against the top aquarium frame. By placing hook pads at two different locations along the length of the cord I was able to situate the fixture at different heights.
Hook & Loop Fasteners
This final picture shows the fixture hung at its low position. Notice that the aquarium cover consisted of simple rectangular pieces of plate glass.
T5 Light Hanging Assembly
I did not have a PAR light meter or similar device for measurement of light intensity, but it was clear that the fixture shined with plenty of intensity for the moderate-light plants in this display. It was noticeably brighter than the lighting that it replaced, a pair of twin-tube, aquarium T5 fixtures. Each lamp in these lights drew 24 watts, so this gardening light, with its superior reflector, consumed a little more than half the wattage while also generating more light.
I might choose to paint the white plastic fixture end caps with a black spray paint so that they will match the aquarium frame.
*Use caution with electrical appliances near water. The manufacturer of this light actually recommends against applying it in any kind of wet situation. This blog post relates the author’s personal experience with this product, but does not endorse its use as aquarium lighting. If the reader chooses to use this lighting fixture or any similar device near water, or with any of the described modifications, they will do so at their own risk.
What’s your feeling on the quality of the fixture’s reflectors? My -limited- research points to reflectors design as one of the key differentiators for T5s - smaller bulb diameter = closer to point (or in this case, line) source = better chance at good reflectors.
I can’t remember the original reference, but I remember reading that well-designed reflectors can increase light-output for fluorescent lamps by nearly 200%.
I’m not an engineer and have very little technical understanding of these matters. I also lack a light meter–I hope to acquire one soon–but my subjective observations suggest that this fixture is a great deal more efficient than the T5 strip lights that it replaced. It looks to me like almost twice as much light, but the lamp is using just a little more than 1/2 the wattage of the lighting that it replaces.
I am also unable to comment on your point about reflector efficiency as it relates to lamp diameter, although I think that I get the general idea. If this relationship were to account in part for the greater efficiency of T5 lamps + polished reflectors, then perhaps the efficiencies of larger-diameter lamps, such as T10 or T8, could be enhanced with larger reflectors. However, reflectors thus designed would be very bulky.
Nice light.
Hydro, no, watt for watt, T10s or 8s wouldn’t be more efficient with larger polished reflectors. T5s are more efficient because they are closer to a “point source” (geometric line) resulting in less restrike - there is simply less surface area of bulb to watt emitted. A reflector around a point source of light would lose no light to restrike, and if the the reflector were perfect, 100% would go in the intended direction.