Giesemann Stellar...OR...Aquatic Life T5/LED hybrid? Reef tank lighting showdown - BRStv Investigates

Hybrid reef tank lighting solutions that combine the even distribution and proven spectrums of T5 fluorescent lighting and the brilliant fluorescence and shimmer of LED aquarium lighting have rapidly risen to be quite popular for a number of reasons. You really are combining all of the best attributes from various aquarium lighting options into a single functioning lighting system.

AquaticLife Hybrid and Giesemann Stellar 24 inch fixtures

Thanks to the Giesemann Stellar and Aquatic Life Hybrid, hobbyists now have easy to install out-of-the-box kits that allow you to utilize the LED light of your choice alongside T5 lamps in a contemporary housing.

Why use a Hybrid?

Being the two most popular hybrid options on the market we decided to compare the PAR and light spread from the 24” versions of each kit to see if they are exactly the same or if one has some advantages over the other.

T5/LED Hybrid over WWC 900 Gallon

T5 lighting is a tried and true lighting technology that delivers plug and play results and coats the aquarium in a very even spread of light. LED lights have a small form factor, are energy efficient and provide a brilliant natural shimmer inside the aquarium and the advanced spectrum control allows users to achieve a level of coral fluorescence like never before.

Combining these two lighting options together gives you the best of both worlds and our very own Ryan has personally stated the T5/LED hybrid is the ideal reef tank lighting solution. Not to mention industry leading coral propagation companies such as World Wide Corals are using these lighting combos to grow corals with the same if not better results than any other lighting option.

Randy using a PAR meter

T5 Only - PAR Values

Getting right into it, we first want to look at the PAR from each of the two fixtures without any LED lights. We are using x4 ATI Blue Plus T5 lamps only and this will give us a good indication of whether or not one fixture is performing better on the T5 side of things.

Measurements are taken from a 24 inch 60 gallon cube shaped aquarium with the fixtures mounted at 8 inches from the water’s surface at depths of 6, 12 and 18 inches.

T5 Only PAR values at 6 inch depth

At 6 inches of depth, the Aquatic Life is averaging about 35 PAR more across the board compared to the Giesemann Stellar. This is most certainly related to the width of the Aquatic Life that positions each bank of T5 lamps 5 inches closer together right out of the box which helps eliminate light spill at the 8 inch mounting height.

T5 Only PAR values at 12 and 18 inches

At the depths of 12 and 18 inches the story remains with Aquatic Life coming in with a higher average PAR across the board.

Considering the design of the Giesemann is a bit wider we dropped the mounting height down until the light spill was eliminated which ended up at about 3” from the water’s surface.

Giesemann Stellar mounted at 3 inches

At 3 inches from the surface this mounting height is pretty impractical when it comes to accessing the tank for maintenance, feeding or various other tasks but none the less we did eliminate the light spill over this 24 inch cube aquarium and were able to actually beat the PAR numbers from AquaticLife.

LED Only PAR Values of Giesemann Stellar at 3 inch mounting height

We recorded the Stellar PAR values again at depths of 6, 12 and 18 inches which boosted the overall average PAR slightly higher than the Aquatic Life.

To wrap up the PAR comparisons, you could reasonably expect similar performance to the Aquatic Life Hybrid mountated at 8 inches by lowering the Giesemann Stellar down to a height of 3 inches. Being so close to the water, however, this is a less than ideal scenario.

LED/T5 PAR value increase with addition of popular LED lights

T5/LED - PAR Values

We have already done some extensive testing with the Aquatic Life Hybrid and taken various par measurements using very popular LED lights alongside the ATI Blue Plus T5 lamps in our video review: BRStv Investigates: Diving into the Aquatic Life T5/LED Hybrid fixture.

Considering our results with the T5 only tests, it is safe to assume that when you add the same popular LED lighting choices to the Giesemann Stellar you would get the same increase in PAR values outlined in the image above. The overall average lower PAR values of the Giesemann would still remain because of the light spillage from the T5s when mounted at 8 inches from the surface.

Options and features

For options on T5 hybrid fixtures it really comes down to the ability to dim the lights, brackets for size adjustments and options for mounting your choice of LED fixtures.

Right now, there’s not an option for a dimmable Giesemann hybrid fixture. Aquatic Life, however, has released their next generation of T5/LED hybrid that is dimmable, uses a single power cord and includes the 0-10v control cable for tying into popular aquarium controllers like the Neptune Systems Apex.

Giesemann end plates

When it comes to adjusting the size, the Giesemann is advertising three different sizes but we could only get our hands on the XL and Standard. The shortening plates will ultimately be the most valuable to the widest variety of reefers based on typical tank sizes and the light spillage we encountered during our PAR tests.

Aquatic Life end plates

The Aquatic Life Hybrid currently has two end plate options available, a shorter 16 inch end plate and the larger 24 inch end plate which really makes this fixture more versatile and usable on a wider variety of tank sizes.

Giesemann LED mounting brackets

For LED mounting options, the Stellar comes with two L-shaped brackets that can slide to any width to support your choice of LED fixture with some double sided tape to secure the LED fixture in place. In application, this is really best reserved for rectangular LED fixtures because any other shape would not allow for a secure mount into the L shaped bracket.

Giesemann also offers universal LED mounting struts separately which would be more practical and secure for mounting non-rectangular LED lights such as the Kessil A360s.

Aquatic Life Hybrid T5 mounting brackets

Aquatic Life includes universal LED hanging brackets to safely secure a wide variety of LED lamps, however, they also offer specialized round brackets specifically for the circular Kessil LEDs.

The available hanging kit for both fixtures is very similar in design with only one difference. Aquatic Life includes the suspension system inside the box while Giesemann’s is sold separately.

Hybrid tank mount options

For those who do not have the ability to hang these hybrid fixtures, tank mount solutions are available for each. The Giesemann Stellar tank mounting kit is suitable for rimless tanks only with a minimum front to back width of 18 inches but ideally >24 inches because of the limited end plate options.

Aquatic Life offers the Universal & Hybrid mounting Kit that works with either rimless or rimmed tanks because it attaches to the stand then extends over the top of the tank giving you an anchor point for the included suspension kit. The single mounting arm will run you $76 each and you would need two of these arms to suspend the fixture which adds on an additional $152 to your overall costs.

Giesemann Stellar end plates and cord rails


In terms of overall physical appeal and how these lighting options look over your tank, the Giesemann Stellar takes the cake because of the sleek textured housing that’s similar to other lighting fixtures they offer like the Matrixx T5.

The Stellar also has two power supply cords much like the original non-dimmable Aquatic Life fixture, however, with the Stellar both cords extend from one side of the light making it easier to manage and hang over the tank evenly.

Cord management is important on these hybrid fixtures and Giesemann did a much better job of providing secure cutouts for the additional cords coming from your LED fixtures.

Giesemann Stellar reflectors and vents

Build Quality

Giesemann Stellar uses a heavier duty aluminum housing and end plate brackets coupled with a rounded more sleek and aesthetically appealing form factor. The reflectors are obviously a higher quality with a more pronounced center that separates each bulb individually so that more light is reflected downward rather than being absorbed by the bulb next to it.

There’s also additional slits in the center portion of the reflector and on the end plates to optimize passive cooling which is something we don’t see addressed by the Aquatic Life fixture.

Hybrid T5 socket side by side comparison

As with all electronic gear being used around water, it is important to take precautions that will reduce the chance of moisture entering the unit. In this case, neither company did an outstanding job.

Giesemann includes the classic twist-in T5 sockets with small acrylic shields protecting the socket area. Aquatic Life utilized a rubber boot type connections to prevent the moisture and bulb clips on either end to hold the bulbs in place.

Reef Fantasy or Reef Certainty Scale

Are the hybrid lighting fixtures from Giesemann and Aquatic life the same?

This one gets a 3 reef fantasy scale because outside of being fundamentally and technologically similar, they are uniquely different. Both units allow you to take advantage of T5 technology and the freedom to choose your LED fixture but PAR output, physical appeal, mounting options and build quality are different, each with its own benefits and drawbacks.

Still curious as to why T5 lighting is still being talked about and used by experienced hobbyists? Ryan did a great job summarizing why this is so in a recent Reef FAQs T5 Reef Lighting - Why T5 continues to be popular with advanced reef tank owners - BRStv Reef FAQs

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