Mars Hydro SP 6500 Review

The New Mars Hydro SP-6500 is an impressive fixture which is designed for commercial scale spaces or grows with supplemental carbon dioxide. It delivers an incredible amount of light for such a small fixture. It is a single LED Bar, but it can easily light up over 20 square feet. It gets great efficiency and distributes the light well. However, it is too much light unless you run supplemental carbon dioxide or have a lot of vertical clearance. In a grow tent, the Mars Hydro SP-3000 (Test Report) continues to be the best bet, but in a grow room, the new SP-6500 could be even better.

Like the SP-3000, the SP-6500 features top of the line Samsung LM301b and Osram 660nm diodes. The SP-6500 packs 2,356 LED diodes onto a 108 x 9cm (42.5” x 3.5”) bar. It has an impressive aluminum radiator which passively dissipates the heat. The SP-6500 is bulkier, but not much larger than the SP-3000.

The Mars Hydro SP-6500 has a published power draw of 650 watts. That is a lot of power to put through the high efficiency components. Using the manufacturer’s data, the Grow Light Calculator estimates that the SP6500 should cover over 20 square feet. I was surprised that Mars Hydro only recommends it for a 5’ x 3’ (15 sq. ft) grow space.

I decided to test it first in the 5’ x 3’ coverage area that Mars Hydro recommends. However, it quickly became apparent that it was too much light to follow my standard protocol in that space. At 50cm above the canopy, I had a maximum PPFD of 1500 with a great distribution of light to the edges.

The PAR map and data from the 5’ x 3’ test are below. The SP-6500 performed great. It had an Average PPFD of just over 1000 µmol/m² and produced a Usable Photon Efficiency of 2.16 umol/w. This would be a great space and height to run the SP 6500 if you are using supplemental CO2, however it is far too much light for most home grow spaces.

I expanded the test area to 5’ x 4’ (20 sq. ft). In that space, I had to raise the SP-6500 to 70cm (27.5”) above the sensor in order to get the Maximum PPFD down to 1000 µmol/m². This test conforms to our protocol and is our official test for the SP-6500.

Although it is only a single bar, the Mars Hydro SP-6500 does a really good job distributing the light to the edges and corners. The high hanging height helps, but the distribution is still impressive. The lowest PPFD value in a corner of the 20 square foot test area was 557 µmol/m².

In the 5’ x 4’ test area at 70cm, the SP-6500 generated an average PPFD of 736.9 µmol/m² and a Usable PPF of 1326.4 µmol. During the test, I measured a power draw of 630 watts (at 120v). That means the SP-6500 delivered 2.11 µmol/w. With a purchase cost under $800 (Use Discount Code: CCFC on Mars-Hydro.com), the SP-6500 has an incredible cost efficiency of less than $0.60/µmol.

Both of the PAR tests that I ran demonstrate strengths and potential pitfalls with using the SP-6500. In 15 square feet, it does an amazing job delivering ultra-high PPFD, but you would need to run supplemental CO2 in order to have success with that set-up. For grows without supplemental CO2 the SP-6500 can easily cover 20 square feet. However, it requires a pretty high hanging height which makes it unsuitable for most grow tents.

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The large radiator on the top of the SP-6500 manages the heat well, but it does get pretty warm. I measured a peak temperature of 65.5 c (141 f) on the aluminum fins. While this may seem high, the fixture itself is not very large relative to the amount of light that it produces. The heat is concentrated in that impressive heat sink, but the total amount of heat added to the space should not be a big concern. Furthermore, the driver is easily located outside of the grow space.

I also tested the dimmer knob. As you can see in the graphic below, the dimmer knob is accurate throughout the dimming range. I figure with a fixture that produces so much light, the dimmer might get a lot of use. However, I don’t really think it is worth investing in the light unless you can run it at its full potential, at least some of the time.

I think the main market for the SP6500 is large grow spaces over 80 square feet. I would recommend one SP-6500 per 20-24 sq. feet. In a large array you will be able to get very even coverage of high-density light. I see it being an excellent option for many commercial grow operations.

The Mars Hydro SP-6500 is too much light for most home growers. However, if you have the right set-up to take advantage of it, there are certainly advantages. It is a well-made fixture with top of the line components. It gets superior Usable Photon Efficiency and generates an excellent distribution of light. At less than $0.60/µmol, it competes with the discount fixtures, but with 2.11 µmol/w it has a performance that rivals the top end brands. If you can handle the light, then I certainly recommend the Mars Hydro SP-6500.