SPECTRAL
ANALYSIS OF 150W DOUBLE ENDED METAL HALIDE LAMPS AND BALLASTS
by SANJAY JOSHI, Ph.D. & TIMOTHY MARKS
Sponsored in part by:
Introduction
The
popularity of double ended MH lamps is on the increase. Their compact
size and the availability of attractive luminaries such as the
Aquaspacelight by Aqualine Buschke, the Nova by Giesmann and others adds
to the aesthetic appeal of reef lighting.In this article, the seventh in the series [1-6], we present a
comprehensive evaluation of most 150W double ended lamps, the ballasts
available to drive these lamps, and a comparison with 175W single ended
lamps.
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A
total of five 150W lamps available within the reef hobby were
evaluated along with the five ballasts used to drive these lamps.
The ballasts tested represent a selection of electronic and
magnetic ballasts that are commonly available to a reef aquarist.
The magnetic ballast used for these tests was a Venture ANSI-M81
ballast. The M81 ballast is recommended for the 150W Ushio 10000K
double ended lamp as listed on their web page (www.ushio.com).
The M81 represents the series of ballasts commonly referred to as
“HQI” in the reef lighting business. Table 1 below shows the
lamps and ballasts used for this study. It should be noted that
while referring to ballasts as HQI may be acceptable, the only
lamp that can be correctly called “HQI” is the OSRAM which
features that trademark.
Table
1:
List of lamps and ballasts tested
150W
Lamps
150W
Ballasts
Ushio
10000K
Reliable
Ballast
Aqualine
Buschke 10000K
Aromat
Ice
Cap 10000K
Ice
Cap
Sylvania
AquaArc 10000K
Hello
Lights
BLV
Colorlite (blue)
M81
Test Setup
In
an effort to test the double ended lamps in a manner similar to our
tests of the mogul based lamps and to allow one to compare their values
to those of mogul based lamps, we used a bracket that enabled us to
suspend the bulb in space interfering minimally with the light emitted
from the lamp. The bracket was painted black to eliminate reflection.
Picture 1 below shows the setup as used during testing. The option of
testing in a commercial fixture with a black painted reflector (similar
to the manner in [7]) was considered, but not used since the method used
here is more in line with how the single ended lamps were tested in our
prior tests. The same Licor Spectroradiometer used in our prior tests
was used, again with the sensor at eighteen inches below the central
axis of the lamp. With double ended metal halide lamps, the lamp
orientation is limited to two directions. All lamps were tested with the
nipple orientation as close to up as was possible given the limitations
of double ended lamps. Spectral data was collected for the bare lamps as
well for a shielded situation, because almost all applications recommend
using these lamps within a glass shielded fixture.A glass shield taken from the PFO fixture was used. This shield
is 1/8” thick tempered, low-e glass (Dave at PFO, pers. comm.)The glass shield was placed on top of the spectroradiometer to
eliminate any stray unshielded light from reaching the sensor.This allowed us to determine the impact of the glass shield on
light output.For each ballast and lamp combination, in shielded and
unshielded state, spectral data was collected amounting to a total of
fifty combinations evaluated (5x5x2 = 50).Additionally, for each ballast and lamp combination the power
consumption, input voltage and current were also recorded using a Victor
True RMS power meter. The power value is what a user pays for when
running the ballast and lamp combination.
Figure
1:
Test setup showing suspended lamp, power meter and
spectroradiometer housed within a black room
The data collected is
presented as follows: The spectral data and light output for
each of the lamps is first compared using a common ballast. This
allows for direct comparison of the spectral differences between
each lamp.The next
section presents the data for each lamp when used with different
ballasts. Efficiency is then presented on a lamp and ballast
basis and finally, a comparison of the 150W DE lamps with 175W
single ended lamps is presented.
SPECTRAL OUTPUT OF THE LAMPS (single ballast)
Since
the ANSI-M81 is the recommended ballast for 150W double ended
lamps, we decided to compare the lamps using this ballast to
establish a baseline of performance.
The
figure below shows the spectral output of the five different
lamps when operated by the same ballast.
Figure 2: Spectral plot showing a comparison
of the spectrum all the 150W DE lamps tested
Figure 3:Light Distribution in different wavelengths of the Lamps
From
the plot in figure 2, the spectral difference between the lamps can be
clearly distinguished.The
Aqualine Buschke (AB), Ushio and Icecap lamps have very similar spectral
distributions with primary differences being in the peak values
achieved, which translate into differences in the color temperature, and
PPFD (PAR) values as shown in Table 2 below.The Sylvania Aqua Arc is an interesting lamp, with a very
different spectral peak as compared to the other 10000K lamps.The BLV Colorlite Blue lamp, as expected, has a single pronounced
peak at 454 nm, very similar to the 20000K lamps sold in the hobby.Figure 3 shows the light distribution grouped into various color
ranges.
Table 2:
Comparison of PPFD, CCT, and Power use of the different 150W DE lamps
with the M81 ballast (unshielded)
Lamp
Power
Voltage
Current
PPFD
CCT
Ushio
10000K
202
119.7
1.83
72.1
6462.8
AB
10000K
191
120.3
1.74
63.9
122229.3
IceCap
10000K
212
120.9
1.89
77.2
9117.1
Sylvania
Aqua Arc
196
121.6
1.77
77.7
7844.8
BLV
Colorlite
202
121
1.82
35.7
Out
of range
As
far as PPFD is concerned, the Sylvania and IceCap lamps have the
highest output, with the IceCap lamp coming closest to its claimed
10000K specification. It is interesting to note that the Sylvania
Aqua Arc lamp, in spite of having lower output in the blue range,
still has a higher CCT than the Ushio lamp. This makes it even more
important to know the spectral output along with the PPFD and CCT
values because color temperature alone is not a precise indication
of where the peak values occur. The AB lamp, as seen from the
spectral plot, has higher peaks in the blue/violet region, and hence
has a much higher CCT. Personal conversations with Brad Shaw
formerly of Aqua Medic had indicated that the AB lamp is in fact a
13000K lamp, and as seen from the test result this lamp did come
close to the claimed color temperature (this result can also be seen
in the data from the other ballasts). Both the IceCap and AB lamps
are excellent choices for an aquarist looking for a crisp white/blue
coloration.
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The
differing UV output of the lamps (310-400nm) is also quite interesting.
As seen from the graph in figure 3, the AB lamp has a considerably
higher UV output as compared to the other lamps, almost 60% more than
the Sylvania lamp and more than double that of the Ushio and Icecap
lamp.
To
determine the impact of using a glass UV shield with double ended lamps,
the lamps were tested with a shield placed over the sensor as was
previously explained.The figures 4 and 5 show the impact of the UV shield on the
lamps’ spectral output, using the AB lamp as an example
Figure 4:AB Lamp output – Shielded vs Non Shielded
Figure 5: Effect of the Glass Shield on the
AB Lamp Output
The
use of the shield resulted in a drop in the PPFD to 50.63 (a 20%
reduction). This 20% reduction in output is pretty consistent across all
lamps.Since these are
intended to be UV-specific shields, as seen from the data, there is a
47% drop in the output in the UV range, and about 27% drop in the
400-440 nm range. Interestingly, the UV shield used on an AB lamp brings
the UV output of the lamp to a range very similar to the UV output of
other lamps without a UV shield. The question that still needs to be
adequately answered is what level of UV emissions is harmful to corals
and other reef tank inhabitants. Also, we did not measure any UV
emissions in the UV-B and UV-C range, given the limitations of the
spectroradiometer being used.
COMPARISON OF LAMPS UNDER DIFFERENT BALLASTS
In
this section we present the results of testing the different lamps using
different ballasts.For
each lamp tested, five 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.
Ushio 10000K:
The
Ushio 10000K lamp is a popular lamp in all wattages. It is commonly
available to reef hobbyists and relatively inexpensive compared to
others. When this lamp is burned next to an AB or IceCap lamp, to our
eye it appeared different in color and the color temperatures that were
found for this lamp support that observation.
Table 3:
150W Ushio 10000K unshielded
Ballast
Power
Voltage
Current
PAR
CCT
Reliable
168
120.5
1.52
64.1
6487.7
Aromat
164
120
1.48
62.6
6526.6
M81
202
119.7
1.83
72.1
6462.8
IceCap
168
120.2
1.49
63.3
6462.9
Hello
Lights
179
119.7
1.74
75.5
5994.2
Table 4:
150W Ushio 10000K shielded
Ballast
Power
Voltage
Current
PAR
CCT
Reliable
166
120
1.52
52.1
6057.1
Aromat
164
120.3
1.48
51.2
6103.2
M81
203
120
1.84
59.3
6044.2
IceCap
168
120.3
1.5
52.3
6028.9
Hello
Lights
178
119.8
1.73
61.2
5679.2
Figure 6: Spectral Plot of the Shielded
Ushio Lamp
Tables
3 and 4 show the test results for the USHIO 10000K lamp with different
ballasts.As seen from the
results there is very little difference between the three electronic
ballasts (IceCap, Reliable and Aromat) with respect to power use, PPFD
and CCT.The ANSI-M81 is the recommended ballast for this lamp
according to USHIO (www.ushio.com)
and it does generate more light output from the lamp, however the power
consumption is much higher.The
Hello Lights ballast used 2% less wattage but provided 3% more PAR for
the shielded results and the color temperature dropped some 6%. However,
this lamp flickered considerably with the Hello Lights ballast. Hello
Lights claims this ballast to be usable for 150W and 175W double and
single ended lamps however the ballast itself only indicates compliance
with 175W lamps. Additionally, there is no switch on the ballast to
designate to the ballast which lamp wattage is being driven. This may be
the reason for the flicker in the light output.
AB 10000K:
This
lamp, manufactured by Aqualine Bushke and sold in the US through Aqua
Medic, is another very popular lamp in the hobby. Again we can see that
there is very little variation between the electronic ballasts driving
the lamp as far as PFFD values are concerned. Interestingly enough, the
lamp had CCT values close to 13000K in the unshielded state.The Hello Lights ballast had the highest PPFD output as compared
to the other ballasts and there was no flicker with this lamp when
powered by the Hello Lights ballast.
Table 5:
150W AB 10000K unshielded
Ballast
Power
Voltage
Current
PAR
CCT
Reliable
168
119.9
1.53
66.1
13033.8
Aromat
163
120.4
1.47
64.2
13155.2
M81
191
120.3
1.74
63.9
12229.3
IceCap
172
119.7
1.54
66.9
12479.3
Hello
Lights
175
119.8
1.72
79
12871.2
Table 6:
150W AB 10000K shielded
Ballast
Power
Voltage
Current
PAR
CCT
Reliable
168
119.7
1.54
53.2
10762.2
Aromat
163
120.7
1.47
51.8
10826.8
M81
191
120.3
1.74
50.8
10209.3
IceCap
172
119.8
1.53
54.2
10756
Hello
Lights
177
120.2
1.72
64.3
10811.5
Figure 7: Spectral Plot ofthe Shielded AB Lamp
The
tremendous peak at 420 nm is clearly obvious as is the smaller secondary
peak at 546 nm.
IceCap 10000K:
This
brand new lamp is being manufactured in Germany and sold by IceCap in
the US. It is a promising new lamp, with excellent PPFD values and CCT
close to 10000K.Here
again, the three electronic ballasts are comparable in light output. The
M81 ballast generates the highest output, but once again has higher
power consumption.
Table 7:
150W IceCap 10000K unshielded
Ballast
Power
Voltage
Current
PAR
CCT
Reliable
167
119.8
1.51
61.8
9195.9
Aromat
164
121.2
1.47
59.8
8902.4
M81
212
120.9
1.89
77.2
9117.1
IceCap
168
120.3
1.51
61.1
8996.7
Hello
Lights
178
119.9
1.71
72.4
8595.3
Table 8:
150W IceCap 10000K shielded
Ballast
Power
Voltage
Current
PAR
CCT
Reliable
166
119.8
1.52
50.3
8270.5
Aromat
164
121
1.48
48.5
7844.6
M81
212
121
1.89
63.6
8190.9
IceCap
168
120.4
1.51
49.9
8074.1
Hello
Lights
178
120
1.71
57.6
8042.6
Figure 8: Spectral Plot of the Shielded
IceCap Lamp
The
similarities between this lamp and the AB lamp are numerous. The largest
difference is in the higher peak at 546 nm and lower peak at 420 nm,
which accounts for the higher PPFD and lower CCT values as compared to
the AB lamp. The IceCap lamp flickered considerably with the Hello
Lights ballast.Overall
this is an excellent lamp.
Sylvania AquaArc 10000K:
This
lamp was actually acquired from Australia and to the best of our
knowledge is not currently distributed within the US. The lamp is listed
on the Sylvania web site (http://www.aquanet.de/sylvania/English/dframset.htm).
Once again there is very little difference between the electronic
ballasts, except for the Hello Lights ballasts which generated the most
output. Similarly to previous lamps, there was considerable flicker
while operating on this ballast.
Table 9:
150W Sylvania AquaArc 10000K unshielded
Ballast
Power
Voltage
Current
PAR
CCT
Reliable
168
120.4
1.53
74.8
8380.4
Aromat
163
120
1.48
72.4
8427.1
M81
196
121.6
1.77
77.7
7844.8
IceCap
172
119.9
1.53
75.7
8338.4
Hello
Lights
178
120.9
1.68
95.1
8153.3
Table 10:
150W Sylvania AquaArc 10000K shielded
Ballast
Power
Voltage
Current
PAR
CCT
Reliable
168
120.2
1.53
61.2
7854.3
Aromat
163
119.9
1.48
59.5
7884.2
M81
196
121.3
1.77
64.3
7431.3
IceCap
168
120.2
1.51
62.9
7846
Hello
Lights
178
120.8
1.7
78.8
7727.1
Figure 9: Spectral Plot ofthe Shielded Sylvania Aqua Arc Lamp
This
lamp’s sole peak occurs at 536 nm which is unique from any other lamp
tested. This lamp does have a high color temperature despite its lack of
significant peaks in the blue or violet spectrum. Although the Hello
Lights ballast achieved the highest PAR values, this lamp flickered
considerably while operating on it. One of the authors (TM) is now using
this lamp above a twelve gallon reef aquarium as the sole means of
lighting. The color appears a crisp white with little green or blue
coloration whatsoever and is very pleasing to the eye.
BLV Colorlite (blue):
The
BLV Colorlite (blue) is a lamp that has caught aquarist’s eyes just
recently. It is a similar lamp to the mogul based Radium in its spectrum
but comes in a double ended format.
Table 11:
150W BLV Colorlite unshielded
Ballast
Power
Voltage
Current
PAR
CCT
Reliable
168
119.5
1.54
30.3
RANGE
Aromat
164
121
1.48
31.8
RANGE
M81
202
121
1.82
35.7
RANGE
IceCap
172
119.8
1.52
32.2
RANGE
Hello
Lights
175
120.5
1.7
34.1
RANGE
Table 12:
150W BLV Colorlite shielded
Ballast
Power
Voltage
Current
PAR
CCT
Reliable
168
119.7
1.54
25.4
RANGE
Aromat
164
120.9
1.47
24.8
RANGE
M81
201
121
1.82
28.9
RANGE
IceCap
172
120
1.53
27.2
RANGE
Hello
Lights
175
120.1
1.69
27.4
RANGE
Figure 10: Spectral Plot of the Shielded BLV Colorlite (Blue) Lamp
As
is plainly obvious, this lamp provides light from primarily the blue end
of the spectrum. The peak occurs at 454 nm.
EFFICIENCY OF 150W LAMPS
One
differentiating measurement of a lamp’s performance is the efficiency.
This measure is the amount of PPFD put out divided by the power
consumed. This measurement allows us to compare lamps of different
wattage and allows a hobbyist to select a bulb that will provide the
most light per dollar spent on electricity (reference to first of your
articles). As electricity is becoming more expensive in some areas, this
measure is a valuable tool in selecting a lighting setup. Below is the
efficiency data for all lamps and ballasts. This data is presented for
the shielded situations only, as that is how a lamp would most often be
utilized over a reef tank.
Table 13:
Efficiency ((uE/sec/m2)/watt)
Ushio
AB
IceCap
ColorLite
Sylvania
Average:
Reliable
0.31
0.32
0.30
0.15
0.36
0.29
Aromat
0.31
0.32
0.30
0.15
0.37
0.29
M81
0.29
0.27
0.30
0.14
0.33
0.27
IceCap
0.31
0.32
0.30
0.16
0.37
0.29
Hello
Lights
0.34
0.36
0.32
0.16
0.44
0.33
Average:
0.31
0.32
0.30
0.15
0.37
As
can be seen from the data, the Sylvania is the most efficient lamp by
roughly 15%, followed by the Ushio, AB, IceCap and lastly, the Colorlite.
In terms of ballast efficiency, note that the magnetic ballast was the
poorest performer and that almost all electronic ballasts performed
identically with the exception of the Hello Lights ballast which was
very efficient but caused flickering on many of the lamps tested.
COMPARISON WITH 175W SINGLE ENDED LAMPS
A question that hobbyist
often encounter is should I go with 150W double ended lamp versus the
175W double ended lamp. A comparison of two such lamps (AB 150W DE and
AB 175W SE) is shown in the table and figure below. As seen from the
data, there is very little difference in the light output of the two
lamps when both are run using the manufacturer’s suggested magnetic
ballast.(Note: The 175W
lamp used here for comparison is the better of the two AB 175W lamps we
tested in our previous article (http://www.advancedaquarist.com/issues/oct2002/feature.htm).
Table 14:
Comparison of the AB DE 150W lamp with the AB 175W Single Ended Lamp
Lamp
& Ballast
Power
Voltage
Current
PAR
CCT
175W
SE- Mag. Ballast (M57)
213
120.3
1.92
64.4
11687
150W
DE- Mag. Ballast (M81)
191
120.3
1.74
63.9
12229
Figure 11: Spectral Plot Showing Comparison
between AB 150W DE and AB 175W SE Lamp
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Another
interesting observation is the fact that there is very little difference
in the UV-A range for the two lamps 150W without a shield and the 175W.The fact that the UV-A flux from similar single- and double-ended
lamps is similar does not in any way imply that it is safe to run
double-ended (single envelope) lamps without UV shielding.The borosilicate glass used as the envelope for single ended
lamps is a good UV-B and UV-C absorber.Both UV-B and UV-C are known to be responsible for a wide range
of potentially damaging human and animal health effects, primarily
related to the skin, eyes, and immune system.Until we know more about the UV-B and UV-C output of the lamps we
do not recommend operating the 150W lamp without a UV glass shield.
Conclusion
The
150W double ended lamps are very attractive choice for lighting, and in
fact we feel they are a better choice when compared to the 175W single
ended lamps – based on the fact they produce as much light as the 175W
lamps and consume less electricity.Also, the smaller size of the lamp makes it more effective in a
reflective fixture.The
electronic ballasts for the 150W lamps are also attractive because of
the size, weight and heat issues, but they seem to slightly under drive
the lamps as compared to the magnetic ballast. Also, it is quite clear
that there is very little difference in the light output for the 3
electronic ballasts, the IceCap, Reliable and Aromat ballast.The Hellolight’s ballast is not likely a true 150W ballast,
since it is rated for 175W also.These results are for new lamps and based on a sample size of
one.Eventually we would like to develop an understanding of how
these double ended bulbs age with different ballast combinations.
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:
Dave and Patrick at PFO Lighting, Brain at HelloLights.com, Brad at
Aqua-Medic, Andy at IceCap Inc.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.
(4)Joshi, S. and Morgan D., “Spectral Analysis of Metal Halide
Lamps – Do Ballasts Make a Difference,” 2001 Annual Marine Fish and
Reef USA, Fancy Publications.
(5)Joshi, S., “Spectral Analysis of Recent Metal Halide Lamps:
Part IV– 10000K and 12000K lamps,” 2002 Annual Marine Fish and Reef
USA, Fancy Publications.
