13 more 250W DE metal halide lamps available within the reef hobby were evaluated along with 2 ballasts used to drive these lamps. The lamps are listed in Table 1. The ballasts used are the “HQI” ballast (ANSI-M80) and the IceCap Electronic Ballast. As usual these lamps were tested using the identical setup to all our previous tests, thus allowing for direct comparison between the lamps.

Spectral Output Of The Lamps (Single Ballast)

Since the ANSI-M80 is the recommended ballast for 250W double ended lamps, we decided to compare the lamps using this ballast to establish a baseline of performance.

Figure 1 below shows the spectral output of the nine different lamps when operated by the same ballast – the M-80 ballast. These spectral plots are for the unshielded lamps (i.e. without the use of any UV absorbing glass shield).

Comparison of Lamp Performance Under Different Ballasts

In this section we present the results of testing the different lamps using different ballasts. For each lamp tested different ballasts were used to fire the lamp and data is presented for the unshielded and shielded case. Spectral data is only provided for the shielded case, since we feel that most lamps will be used in this manner.

1) XDE 10000K

2) XDE 20000K

3) CORALVUE 20000K

4) SUN AQUATICS 20000K

5) SUN AQUATICS 14000K

6) SUN AQUATICS 10000K

7) AQUACONNECT 14000K

8) GIESEMANN MEGACHROME 13000K

9) GIESEMANN 20000K

10) ARCADIA 14000K

11) HIT (BLV) 20000K

12) HELIOS 20000K

13) HELIOS 12500K

Discussion and Conclusion

Figure 15, and 15 show comparison of power and PPFD of the various lamps tested. Once again as seen from the data and plots, there is wide variation among the lamps and the use of CCT to designate the lamps is pretty much meaningless given that the spectral plots are often very similar yet the lamps are being sold with different color temperatures. The usual disclaimer applies – this data is based on a sample size of one, and we have no idea what the variation is within lamps. The HQI 80 ballasts tends to consume much higher wattage than the rated 250W, while the electronic ballast tends to stay close to the rated power of the lamp. The implications of consuming more power are obvious – more light output, however if this detrimental to lamp life remains to be seen.

Comparing the data here and other 250W DE articles with the data for 250W Mogul lamps, should provide enough factual information to dispel the myth that 250W DE lamps produce more light output than the 250W single ended mogul lamps. A general sweeping statement to this effect cannot be made, and depends on the lamp under consideration.

Acknowledgements

We would like to thank several people whose help made this study possible. They were kind enough to provide us with lamps and ballasts for testing: Patrick at PFO Lighting, Brian at HelloLights.com, Andy at IceCap Inc, Phil at Giesemann, Edward at Aquaconnect, Venki at Sun Aquatics, TAAM for the Helios lamps, Chris at Hikari Sales, and Moonpod at RC. Finally, we would like to thank Dr. Paul Walker of Penn State University for the use of the spectroradiometer and dark room for testing the lamps.

References

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