Analyzing Reflectors: Part 3

by | Mar 15, 2004 | 0 comments

In Part I and II of this series [1, 2], we presented the data on 400W single ended mogul reflectors, designed primarily to be retrofit into existing canopies, and 250W Double ended reflector fixtures. This article continues in a similar vein and presents the data and analysis of several additional reflectors that we were able to obtain since the last set of tests.

Table 1: Listing of the Reflectors Tested
PFO IlluminatorMagnetic Ballast (M59)Ushio 400W 10000K
SuperSun IV – Sunlight SupplyMagnetic Ballast (M59)Ushio 400W 10000K
Reef Optix I – Sunlight SupplyMagnetic Ballast (M59)Ushio 400W 10000K
Small Diamond LightPFO HQI Ballast (M81)Vion 250W 10000K
Regent DIY 150W Double EndedReliable Ballast (electronic)AB 150W 10000K
Giesemann 250W Nova IIGiesemann Ballast (electronic)AB 250W 10000K
Giesemann 150W Nova IIGiesemann Ballast (electronic)AB 150W 10000K

PFO’s Illuminator and Sunlight Supply’s SuperSun are designed primarily for horticulture use, but given that we tested the Diamond Lighting’s Lumen Arc III which is also a reflector designed for horticulture applications, we felt it would be interesting to test a few other horticulture reflectors. Diamond Light also makes a smaller reflector (called LA3) which is more suited for 250W single ended mogul lamps (it does not accommodate the 400W lamps as they are too long to fit in this reflector). The small Diamond Light reflector’s results are also shown here. Unfortunately, when this reflector was tested the only available 250W lamp on hand was a Vion 250W lamp (not the best lamp in its class and is no longer being sold). So this data cannot be directly compared to the 10000K lamps and reflector systems, however, the % distribution plots of this reflector would provide useful data for comparison purposes.

The two Giesemann Nova II fixtures are also a choice available to the discerning aquarist especially those interested in aesthetically pleasing designs and good quality, and these reflectors are also tested here.

As avid DIY’ers ourselves, we also explored a cheap version of the 150W double ended reflector system made by retrofitting a Regent 500W Halogen lamp fixture. The allure of this fixture is the fact that it can be easily purchased at Lowe’s or Home Depot for about $10, and with a small retrofit of replacing the halogen sockets with the sockets for the 150W double ended lamps, one could make a very cheap reflector for about $20 and change.

The basic methodology and experimental setup is identical to the one used in the previous set of articles (part I and II, references [1] and [2]). The data is also presented in an identical manner with plots for light dispersion for each reflector at distances of 6″, 9″ and 12″ from the center of the lamp. This article is intended to be a continuation of the previous articles and hence should be read in conjunction with the other two articles.


Reflector Data And Analysis

The data plots for each reflector at the distances 6″, 9″, and 12″ are plotted as a surface graph, top view graph, and a % distribution graph to illustrate the intensity and spread at different points on the measuring grid. Table 2 below shows the list of figures associated with each reflector.

Table 2: List Of Figures Associated With Each Reflector
PFO IlluminatorFigs. 1-3
SuperSun IV – Sunlight SupplyFigs. 4-6
Reef Optix I – Sunlight SupplyFigs. 7-9
Small Diamond LightFigs. 10-12
Regent DIY 150W Double EndedFigs. 13-15
Gieseman 150W Nova IIFigs. 16-18
Gieseman 250W Nova IIFigs. 19-21

One of the measures of a reflector performance could be its ability to direct light into the aquarium. A reflector’s total incident light upon a surface of a given area is representative of the performance of a reflector. It is computed by adding up all the measurements taken at the discrete points within the region. It demonstrates how much light the reflector is able to focus downward when compared to other reflectors with similar operating conditions (same ballast and lamp). While it can be argued that adding all the PPFD values is technically not a valid measure as per the definition of PPFD (since PPFD is defined as μEinstein/m2/sec), it can be used to provide a metric for reflector performance. Further summing over the data points on a given area can easily be used to compute the average, if so desired. Since the area under consideration is the same for all reflectors, we can just as well use the sum of the PPFD values distributed over this area (169 data points) instead of an average as a performance metric.

Table 3: Total Incident PPFD on a given Surface area.
Reflector:Distance:Total Incident LightMaximum PPFD
3×3 Area2×2 Area1×1 Area
PFO Illuminator6″4538843285311402147
SuperSun IV – Sunlight Supply6″4458543867321032150
Reef Optix I – Sunlight Supply6″4422342290301682547
Small Diamond Light6″2730826700218571698
Regent DIY 150W Double Ended6″1704617046149851706
Giesemann 250W Nova II6″3208531875284543360
Giesemann 150W Nova II6″1571515596140481683

As can be seen from this data, the 2 horticulture reflectors (PFO Illuminator and Sunlight Supply’s Super Sun IV) and the Reef Optix are very similar in performance. We have found that reflectors with the ends closed tend to perform better. The Giesemann Nova II fixtures, while very aesthetic and thoroughly designed, could benefit specifically from improved reflector design.

In addition to knowing how much light is incident on a given area, we could also look at how much loss of light occurs on a given area when moving the lamp and reflector higher. Table 4, presents the % of light lost on a specified area as one moves the lamp/reflector from 6″ to 12″ above the surface. A higher % loss would indicate that the reflector is creating a larger spread.

Table 4: Percent of PPFD lost from 6″ to 12″ from the lamp
Reflector3×3′ Area2×2′ Area1×1′ Area
PFO Illuminator133053
SuperSun IV – Sunlight Supply72550
Reef Optix I – Sunlight Supply102438
Small Diamond Light132244
Regent DIY 150W Double Ended191949
Giesemann 250W Nova II51642
Giesemann 150W Nova II55049

Another metric to analyze reflector performance could be to determine the area coverage of a specified amount of light. Although it is difficult to determine exactly what this specified minimum PPFD values should be, we have chosen a cut off of 500 PPFD and present the area coverage plots of each of the reflectors in Figures 22,23, and 24.


Figure 22









Figure 23









Figure 24









Figure 1: PFO Illuminator









Figure 2: PFO Illuminator TOP View









Figure 3: PFO Illuminator – %









Figure 4: Sunlight Supply – SuperSun IV









Figure 5: Sunlight Supply – SuperSun IV Top View










Figure 6: Sunlight Supply – SuperSun IV %









Figure 7: Sunlight Supply – Reef Optix I









Figure 8: Sunlight Supply – Reef Optix I Top View










Figure 9: Sunlight Supply – Reef Optix %









Figure 10: Small Diamond Light – LA3









Figure 11: Small Diamond Light – Top View









Figure 12: Small Diamond Light – %









Figure 13: Regent DIY









Figure 14: Regent DIY – Top View









Figure 15: Regent DIY – %









Figure 16: Giesemann Nova II 150W









Figure 17: Giesemann Nova II 150W – Top View









Figure 18: Giesemann Nova II 150W – %









Figure 19: Giesemann Nova II 250W – PAR









Figure 20: Giesemann Nova II 250W – Top View









Figure 21: Giesemann Nova II 250W – %









Figure 22: 500 PPFD Cuttoff for 400W Reflectors










Figure 23: 500 PPFD Cutoff for 250W Reflectors










Figure 24: 500 PPFD Cutoff – 150W Reflectors








This article is the 3rd in this series and presents the data and a brief analysis of several additional commercially available reflectors. The data provided shows clearly the differences between the reflectors, and can provide the reader with useful data on the light distribution patterns and shapes, which in turn can be used for purposes of aquascaping and placement of corals.



We would like to thank several people whose help made this study possible. They were kind enough to provide us with lamps, reflectors and ballasts for testing: Patrick at PFO Lighting, Brad at Sunlight Supply, Phil at Xenia Inc. for the Giesemann fixtures, Shane Graber for the use of his small diamond light reflector, and Brian at



  1. Joshi, S. and Marks, Timothy. 2003. Analyzing Reflectors: Part I – Mogul Reflectors
  2. Joshi, S. and Marks, Timothy. 2003. Analyzing Reflectors: Part II – Mogul Reflectors
  • Sanjay Joshi

    Sanjay Joshi in real life is a Professor of Industrial and Manufacturing Engineering at Penn State University. He has been a reef addict since 1992, and currently keeps several reef aquariums at home including a 500G SPS coral dominated reef. He also co-manages the 500G aquarium at Penn State. He has published several articles in magazines such as Marine Fish and Reef Annual, Aquarium Frontiers, Aquarium Fish, and Advanced Aquarist. In addition, he has been an invited speaker at several marine aquarium society meetings in the US and Europe. He received the MASNA award in 2006, for his contributions to the marine aquarium hobby.


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