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This is 6cm deep and 24.5cm wide.
When correctly mounted, the base of the Luminaire is raised 7cm above the glass rim of the aquarium, when positioned with the hood down.
The length of the Overtank Luminare bracket is 23.5cm.
Not, only that, but the electronic components used to power the 150W versions are not the same as those used to power the 250W versions. Basically, the entire internal workings would need to be altered.
The only parts common to the two models are the outer body and the cover glass.
Once the unit had been returned and altered, the cost of the parts and labour involved would be no saving on purchasing a new 250W unit.
For this reason, it is important when purchasing a pendant, to take the time to decide which model is correct for you.
It is therefore essential that all metal halide systems are mounted in such a way that allows the correct level of ventilation, which rules out the oprion of enclosing them within an aquarium hood.
To change a pendant from freshwater to marine (or vice versa), it is simply a case of purchasing the required lamps/tubes and swapping them over - all other components of the pendant are identical.
The largest Overtank Luminaire is 150cm. However, I would like to use one over a slightly larger tank, do you have any suggestions?
1) To attach, using an aquarium silicon sealant, some suitably strong bars across the width of the tank. Ensuring that these bars are placed at suitable frequencies for the 150cm unit to mount on and then mount the Overtank Luminaire onto the bars rather than directly onto the aquarium ruim.
2) Alternatively, suspend the 150cm Overtank Luminaire from the ceiling, using the Overtank Luminaire Suspension kit, which can be ordered from all good retailers.
What are the different types of fluorescent lamps?
Linear lamps are the most common, and come in several widths.
The most common European width is now the 1” lamp, which is 26mm, but it is also known as a T8 lamp. Each “T” represents an eighth of an inch, therefore 8 x 1/8 = 1”.
The old style of linear lamp was the 1 1/2” lamp, or T12 lamp, which is 38mm in the EU.
Short lengths are sometimes 5/8” (16mm) in width, known as T5 lamps. Recently, T5 lamps have become available in longer lengths too; these need electronic ballasts to run, and produce some 50% more light per linear length than standard T8 lamps.
Special applications can use either T1 or T2 lamps, but their application is rare.
The wavelengths (colour) radiated by the phosphors vary with the chemicals used. Old lamp technology uses halo-phosphates, which contain calcium, antimony, chlorine, fluorine and manganese. With no manganese the colour of the lamp is blue and by adding different amounts of manganese, blue-white and white to yellow-white lamps are obtained. Halo-phosphates output light fairly evenly over the visible spectrum.
New technology lamps are known as tri-phosphors. The phosphors used are selected to produce high-energy spectral band emission at the 3 critical frequencies which correspond to the red, green and blue of our eye’s perception. Thus, the light emitted appears far brighter than a halo phosphate lamp.
Tri-phosphors are made with a combination of expensive rare earth elements. There are 30 such elements, all found in group 3 of the periodic table, and the 6th and 7th periods.
By mixing the different elements available, it is possible to tailor make the SPD (“spectral distribution”) and the colour temperature of the lamp.
Lamps without phosphors emit ultra violet, including dangerous UVC, and are known as germicidal lamps. They are usually made with a more expensive quartz glass, so that the UV is transmitted through it.
The arc formed within a fluorescent lamp does not have to travel in a straight line. Thus, non linear lamps can be manufactured. The early versions of these were circular lamps, but later, compact lamps were manufactured. These come in a variety of forms, and nearly all of then require an electronic ballast to operate. In many household compact fluorescent lamps, the ballast is built into the lamp base.
These lamps run cooler than conventional linear lamps, and are more energy efficient.
A compact lamp of 20W has the equivalent light output of a 100W incandescent lamp, for example. That’s because most of the energy from an incandescent lamp is wasted in heat.
One must be very careful in specifying an electronic ballast for a compact lamp. An electronic ballast for a linear T8 lamp will not run an 18W compact lamp.
A further area of difficulty is with the lampholder. There are several different lamp holders for compact fluorescent lamps, each requiring a different lamp holder.
Compact lamps are sometimes referred to as PL or PLL lamps, which are all “2 finger” lamps. The PL designation refers to lamps of 5, 7, 9 and 11 watts. The PLL designation refers to lamps of 18W or more, namely 24, 36, 40, 55 and 96 watts. The term PLC, refers to cluster lamps, which have more than 2 fingers.
Some lamps, such as sun bed lamps, have an internal reflector to direct light to where it should be. Efficiency is thus improved.
The extreme reflector lamp is the aperture lamp. Where only a narrow slit is available for the light to exit. These specialist lamps are used for edge lit signs.
Fluorescent Lamp Reflectors
Rays coming from the bottom half, illuminate the water as desired, but any rays coming from the top of the tube hit the inside of the aquarium hood and are wasted.
If a reflector is placed above the tube, these rays are bounced back towards the water, and so 100% of the tubes output is being directed where you want it - into the tank.
Alternativley you can contact our Sales and Customer Services Department. See below:
Tel: +44 (0)1737 72 3838
Fax: +44 (0)1737 72 3815
Using more than one tube increases light intensity, and further encourages plant growth.
Also, different and pleasing effects can be created by combining tubes of different outputs such as the 'Original Tropical Lamp' and the 'Freshwater Lamp'.
In the case of a marine reef tank lit by tubes, then a single tube such as the 'Marine White' is definitely not enough, as an Actinic Blue tube should be used in conjunction - If desired, this can be left on, on its own to create a moonlight effect.
Therefore, we recommend that at the start of each season a new lamp is fitted so that the output is at the strongest level.
The first is when new, the IP67 special sealing ring is more rigid when used for the first time. By administering a small amount of Vaseline (non petroleum based) or silicon grease will assist the ring in sliding over the tube more freely. This will also allow for easier ongoing maintenance.
The second is due to heat dissipation from both types of fluorescent tubes used (T5/T8) and the special IP67 tight sealing mechanism, (designed to prevent water ingress) this can lead to the sealing ring sticking to the tube over a period of time used. To prevent the long term damage of the IP67 sealing ring we recommend lubricating the ring with a small amount of Vaseline (non petroleum based) or silicon grease at the initial installation to enable easier maintenance to be carried out when replacing lamps.
Screw cap replacements are available at the online spares store.
Metal Halide Lamps
When using the Arcadia 14,000Kelvin lamp in a 4 Series pendant, the light output is being maximised by a specially designed reflector which focuses the light into the aquarium.
The fluorescent Marine blue actinic tubes that are fitted into the pendant, supplement the HQI lamp by enhancing the natural fluorescence possessed by many invertebrates, and also give the option of dawn/dusk periods.
The exceptionally high light output when compared to other lamp types such as fluorescent tubes, makes them a very effective light source, particularly for the larger tank set-up.
Magnetic Controllers / Electronic Controllers
I see that a Twin model controller is available for 24W or 39W models. Can two different sizes of lamps be used on the same controller?
Inside a fluorescent lamp, there is an arc of electrical current running from one cathode at the end of the lamp to the other. This arc needs some encouragement to form in the first place, and this is where the starter switch is required. The cathodes of the fluorescent lamp need pre-heating before this arc can be formed. The fluorescent starter switch is effectively a time delay switch, enabling this to happen.
Without a starter switch, the lamp will just flicker, and a continuous arc with not form
Electronic ballasts have the starter function built into their circuitry.
In principle how does it work?
When you turn on a fluorescent lamp, the starter switch ensures that the current flows through the ballast and through the cathodes of the lamp, but there is no arc formed through the lamp.
The cathodes at the ends of the lamp are heated by electricity, the molecules in the cathode become excited, and electrons are liberated into the lamp. The starter switch then opens, forcing the current to form an electrical arc in the lamp, causing the lamp to light.
In practice how does it work?
Inside the starter switch canister, there is a bimetallic strip, which is contained within a small glass envelope containing argon gas. This is a strip of metal made of two different types of metal, each having a different rate of expansion. Thus, when heated, the strip bends.
When the current is first switched on, the bimetallic strip is straight, and its contact open, so the current going through the starter switch goes though the argon gas in the form of an arc. The current is only flowing through the fluorescent lamp cathodes at this point. The argon gas heats up, causing the bimetallic strip to bend towards the other contact of the starter until the two contacts close. The argon arc no longer operates and as the source of the heat is removed the bimetallic strip cools and begins to straighten until the contacts open again.
The opening of the contacts forces the current to form an electrical arc in the lamp, causing the lamp to light. As the current flow is now through the lamp, the starter switch is effectively left out of the circuit, as there is no longer enough voltage available to cause another arc in the argon within the starter switch.
Lamps used in conjunction with starter switches, are sometimes called pre-heat lamps, due to the need for their cathodes to be preheated.
If however your tank is one containing African rift valley cichlids, such as those from Lake Malawi, then a good alternative is to use the Marine white lamp.
Although these cichlids are not marine, the bright colours of fish such as Labidochromis, Haplochromis, or Tropheus do stand out well against the intense white provided when you use the marine white lamp.
It would not be necessary to use the Actinic blue lamp as it would in a marine reef aquarium (although it could still be used to create a moonlight effect if that was desired). Alternatively, if you have the facilities for multiple tubes, then you could use more of the marine white - this would certainly be beneficial for any algae grazing mbuna, as it would increase the availability of their favourite food.
The spectrum diagrams below the lighting types above show the high levels of reds and oranges in the warm light spectrum (3200K) and the change to high blues and no reds/oranges in the cooler lighting spectrums ( 5,600K).
Low colour temperatures (yellows, oranges and reds) 2500-3000K (warm)are at one end of the scale while high colour temperatures (blues and greens) 6000- 20000K (cool) are at the other end.
There are two main types of test colours used, one is the basic (R8) test colours which have eight different colours and the extended R9 range of test colours which add another 6 colours to the original 8 making 14 test colours.
Some species have specialised lighting requirements or levels for optimum environment factors. The correct lighting levels and lighting regime can provide increased immunity, less stress and optimum breeding requirements for fish.
Arcadia have spent over 40 years specialising Arcadia lighting systems for the inhabitants of your aquariums.
Next is IP67 which means it is waterproof and although it is not submersible it has been tested to being temporarily submersed for 30 mins in water. This will only be relevant to part that is IP67 tested, not the whole luminaire.
IP64 is generally accepted as a splash proof requirement and out of the three mentioned is the lowest level of safety protection for a luminaire. (By suspending the luminaire from a suspension kit, a reduced level of safety requirements are required to be met. Thank if the unit was to be fitted to the aquarium.)
Image 1 Image 2: OSRAM LED Lighting products Image 3
The LED is made of material that is doped with other material types to provide what is called a p-n junction, and when electricity is supplied to the anode (P-side of the junction), the diode will conduct a current through the material to the cathode (N-side) of the junction and emit energy at a visible light wavelength that is related to the energy dropped across that junction. It will only allow current to flow in one direction it will not flow in reverse ie cathode to anode. The colour of light emitted is related to the drop of energy across this junction and the type of material used to make the diode.
PAR is a measurement used to determine the strength of the visible lighting spectrum 400 - 700nm that is available to be used for photosynthesis, by plants and most marine corals. It is measured in microeinsteins per second per square meter (μE/m2/sec)
PUR stands for Photosynthetically Useable Radiation.
PUR is the specific part of the lighting spectrum that is used by the organism in question. This may be within the blue part of the lighting spectrum or the red part of the lighting spectrum or both but it will be required by the organism to create photosynthesis.
Pond Lighting – UVC Fluoresecent Lamps
The lamps should never been looked at directly as this can cause serious and painful damage to the eye. In addition UVC is the Ultra violet light that can create severe burning on the skin and could result in skin cancer.
All Arcadia UVC lamps are clearly packed to avoid any confusion.
These lamps also appear see-through and are unlike the rest of the Arcadia lamp range.
If in doubt, consult your retailer.