Since their introduction in the last few months, the XM 15000K metal halide lamps have generated a lot of interest. This article presents a complete analysis of these lamps. The lamps and ballasts used for the evaluation are presented in Table 1 below. As usual these lamps were tested using the identical setup to all my previous tests [1], thus allowing for direct comparison between the lamps.

Table 1: List of XM 15000K lamps and ballast tests reported in this article

Lamps	Ballasts
XM 400W 15000K (Mogul base)	PFO-HQI Taiwan - HQI Standard Magnetic (M59) IceCap (Electronic) Blueline (Electronic) Reef Fanatic (Electronic) EVC (Electronic) Coralvue (Electronic)
XM 250W 15000K (Mogul base)	FO-HQI (ANSI -M80) Standard Magnetic (M58) IceCap (Electronic) Blueline (Electronic) Reef Fanatic (Electronic) EVC (Electronic)
XM 250W 15000K (Double Ended)	PFO-HQI (ANSI -M80) IceCap (Electronic) Blueline (Electronic) Reef Fanatic (Electronic) EVC (Electronic)
XM 175W 15000K (Mogul Base)	Standard Magnetic (M57) Lumen General (Electronic)
XM 150W 15000K (Double Ended)	HQI Icecap (Electronic)

XM 400W 15000K

Table 2: XM 400W 15000K performance on all ballasts

Ballast	Power Watts	Input Volts	Input Amps	PPFD	CCT	Efficiency PPFD/Watt
Magnetic -M59	452	123.2	4.0	104.7	0	0.2316
PFO-HQI	512	121.3	5.55	114.8	0	0.2242
Blueline	383	122.2	3.27	75.4	0	0.1969
Reef Fanatic	428	122.5	3.64	83.9	0	0.1960
EVC	418	121.4	3.59	85.4	0	0.2043
Icecap	416	122.9	3.5	82.2	0	0.1976
Taiwan - HQI	457	122.2	4.01	106	0	0.2319
Coralvue	453	121.2	3.87	103.8	0	0.2291

Figure 1: Spectral data for XM 400W 15000K Lamps on all ballasts

XM 250W 15000K Mogul Base

Table 3: XM 250W 15000K Mogul Base performance on all ballasts

Ballast	Power Watts	Input Volts	Input Amps	PPFD	CCT	Efficiency PPFD/Watt
Magnetic (M58)	295	122.8	2.82	55.7	0	0.1888
PFO-HQI (M80)	352	124	3.18	80.2	0	0.2278
Blueline	253	122.6	2.17	41.9	0	0.1656
Reef Fanatic	256	123.1	2.2	53.2	0	0.2078
EVC	272	122.4	2.33	50.6	0	0.1860
Icecap	255	123.2	2.29	47.6	0	0.1867

Figure 2: Spectral data for XM 250W 15000K Mogul Base Lamps on all ballasts

XM 250W 15000K Double Ended Lamps

Table 4: XM 250W 15000K Double Ended Lamps performance on all ballasts (unshielded)

Ballast	Power Watts	Input Volts	Input Amps	PPFD	CCT	Efficiency PPFD/Watt
PFO-HQI	288	122.7	2.72	56.3	15714	0.1955
Reef Fanatic	255	123.6	2.18	61.6	39197	0.2416
Blueline	250	120.8	2.19	55.4	16126	0.2216
Icecap	242	122.8	2.28	53.3	21981	0.2202
EVC	272	122.0	2.33	66.8	16404	0.2456

Figure 3: Spectral data for XM 250W 15000K Double Ended Lamps on all ballasts (Unshielded)

Table 5: XM 250W 15000K Double Ended Lamps Performance on all ballasts (Shielded)

Ballast	Power Watts	Input Volts	Input Amps	PPFD	CCT	Efficiency PPFD/Watt
PFO-HQI	288	122.7	2.72	45.5	12898	0.1580
Reef Fanatic	255	123.6	2.18	49.6	22625	0.1945
Blueline	250	120.8	2.19	45.4	13115	0.1816
Icecap	242	122.8	2.28	43.5	16099	0.1798
EVC	272	122.0	2.33	54.9	12854	0.2018

Figure 4: Spectral data for XM 250W 15000K Double Ended Lamps on all ballasts (Shielded)

XM 175W 15000K Mogul base

Table 6: XM 175W 15000K Mogul base performance on all ballasts

Ballast	Power Watts	Input Volts	Input Amps	PPFD	CCT	Efficiency PPFD/Watt
M57	198	124.4	2.06	39	0	0.1970
Lumen General	181	124.4	1.63	35.8	0	0.1978

Figure 5: Spectral data for XM 175W 15000K Mogul base Lamps on all ballasts

XM 150W 15000K Double Ended

Table 7: XM 150W 15000K Double Ended performance on all ballasts (Unshielded)

Ballast	Power Watts	Input Volts	Input Amps	PPFD	CCT	Efficiency PPFD/Watt
Icecap	172	123.2	1.46	33.5	14182	0.1948
HQI	181	123.2	1.62	30.9	11004	0.1707

Figure 6: Spectral data for XM 150W 15000K Double Ended Lamps on all ballasts (UnShielded)

Table 8: XM 150W 15000K Double Ended performance on all ballasts (Shielded)

Ballast	Power Watts	Input Volts	Input Amps	PPFD	CCT	Efficiency PPFD/Watt
Icecap	172	123.2	1.46	26.5	14300	0.1541
HQI	181	123.2	1.62	25.18	13094	0.1391

Figure 7: Spectral data for XM 150W 15000K Double Ended Lamps on all ballasts (Shielded)

Discussion and Summary

A question of interest for most hobbyists is - How do this lamps compare to the XM 20000K lamps.? Table 9 shows a comparison of the PPFD values for the XM 15000K lamps and the XM 20000K lamps. What is interesting to note is that several of the lamps - the 250W mogul ended, 250W DE, and 150W DE lamps had in fact correlated color temperatures around 15000K. For the other lamps the Licor software used with the spectroradiometer was unable to compute the correlated color temperature. Spectral plots of all these lamps on "HQI" ballasts (except 175 which is on magnetic ballast) are shown in figure 8. They all have very similar spectral shape, yet the color temperature was not computable in all cases (More on Color Temperature in a future article).

Table 9: Comparison of PPFD with XM 20000K lamps

Lamp	Ballast	PPFD XM 15K	PPFD XM 20K
400W Mogul	Magnetic -M59	104.7	128
	PFO-HQI	114.8	98
	Blueline	75.4	91
	Reef Fanatic	83.9	96
	EVC	85.4	94
	Icecap	82.2	99
	Taiwan - HQI	106	114
	Coralvue	103.8	na
250W Mogul	Magnetic (M58)	55.7	73
	PFO-HQI (M80)	80.2	79
	Blueline	41.9	na
	Reef Fanatic	53.2	61
	EVC	50.6	na
	Icecap	47.6	53
250W DE (unshielded)	PFO-HQI	56.3	55
	Reef Fanatic	61.6	na
	Blueline	55.4	na
	Icecap	53.3	44
	EVC	66.8	na
150W DE (unshielded)	Icecap	33.5	32
	HQI	30.9	28
175W Mogul	Magnetic (M57)	39	na
	Lumen General	35.8	na

na - data not available

Figure 8: Spectral plots of all XM 15000K lamps on "HQI" ballasts

A comparison with the spectral plot of a XM 20000K lamp is shown in figure 9. As seen from the figure, the XM 15000K when compared to a XM 20000K on the same ballast does have less output in the blue region at 454nm and 420nm, and has higher output from 460 nm -700nm (except for around 550 nm). This would tend to indicate that this lamp would appear less blue than a XM 400W 20000K lamp and hence a rating of 15000K.

Figure 9: Spectral comparison of a XM 400W 15000K lamp with a XM 20000K lamp

Comparison of the 250W Mogul XM 15000K with its 20000K counterpart reveals very similar results to that of the 400W lamp, as seen in figure 10, and similarly for the 250W DE lamps as seen in figure 11.

Figure 10: Spectral comparison of a XM 250W 15000K lamp with a XM 20000K lamp

Figure 11: Spectral comparison of a XM 250W DE 15000K lamp with a XM 20000K lamp

Acknowledgements

I 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: Jason Ghee from Hellolights.com for supplying the lamps used in this study, Patrick at PFO Lighting, Andy at IceCap Inc, Perry at Sunlight Supply, Vince at Ocean Encounters, Champion Lighting, and Reef Fanatics for the ballasts. Finally, I would like to thank Dr. Paul Walker of Penn State University for the use of the spectroradiometer.

References

[1] www.reeflightinginfo.arvixe.com