Mars Aqua 300 watt LED modification

Lighting in a reef tank is very crucial. Corals need light in a specific spectrum in or order to grow and stay healthy. Of course there’s more than just lighting in reefing but this post will focus mainly on the modification of the Mars Aqua light. The factory Mars Aqua 300 watt light is actually not bad as you’ll see that it actually outputs at around 14000 kelvin with pars in the 400+.  It’s a great “bang for your buck” setup.

The purpose of this project is to replace my current 3 x Ecotech XR30pro Gen4 with the two Mars Aqua.  As I’m on a tight budget, I’d like to uses the radions for a display tank and I feel my QT tank would do fine with the Mars Aqua.  I’ll be running two 300 watt Mars Aqua on a 40 breeder to ensure that spread is even across the tank.  Hopefully this will provide the coverage needed like good old traditional T5 setups.  Before switching out the lights, I’m going to modify them and shift the spectrum a bit; closer to the 20k range for day light channel.

NOTE: This post may contain affiliate links which pays me a commission fee to offset the cost of running this website. 

Here’s the layout of the LEDs.  I’m assuming it’s correct as I have no way telling.

Below is the LED layout based from what I can tell and from what I’ve found while googling.  The highlighted yellow is the daylight channel and the other is the blue channel.

LED Layout

Get your Mars Aqua here:

You can download the spreadsheet here: MARS AQUA LED UPGRADE.

So for the PAR test, I’m going to utilize the Seneye Reef Monitor.  It’s a great monitor that really works well.  Seneye Reef Monitor is an all in one monitor for Temperature, Ammonia, pH, Water level, and Lighting.  With a PC you can connect your Seneye monitor directly to any PC or Seneye Web Server to monitor your aquarium.  You can monitor your aquarium from anywhere you can get internet access via smartphone, PC or tablet.

This is the same unit I have. Check it out here:

Here’s what it can do:

  • Automatically monitors multiple key parameters
  • Constantly watching your aquarium, 5600 readings per month
  • Healthier coral, integrated LUX, Kelvin and PAR light meter
  • Early warning, intelligent software predicts future water conditions*
  • Convenient alerts sent to e-mail and mobile phone*
  • Access results worldwide, data stored online for easy viewing*
  • Track your results with automatic graphing*
  • USB connection with multiple connection options, including optional USB power adaptor

What does it do? 

Constantly monitors water temperature, so you can get an alert if your heater breaks or your chiller fails
Free Ammonia
Monitors the highly toxic free ammonia (NH3) at very low levels, so you can stop your fish from dying from Ammonia posioning.
The Seneye monitors pH in your aquarium or pond water between 6.4 and 9. This range is ideal for most aquatic life and by focusing on this range increased accuracy has be achieved.
Water Level
Readings are only taken when the Seneye device is in water, no false readings.
Monitors ambient LUX and can be used to take direct LUX readings, understand how your light degrade over time.
Understand where on the kelvin range your lights are and how light can change over time.
Monitor the Photosynthetically Active Radiation (PAR), understand if you have the correct quantity and quality of light for your corals or plants.

I bought the Seneye just for PAR reading so that I’ll know what PAR level my corals are receiving.  All the other features where an added bonus. Using the PAR meter, I’ve made some initial test by reading each LED light to see what spectrum I am getting.  Side note, the Seneye cannot read Kelvin when excessive blue spectrum lighting is introduced.

PAR meter on the RED LED

The Kelvin could not be captured in this image but one can tell that it’s peaking more of the red color.


PAR meter on the GREEN LED


PAR meter on the WarmWhite LED


Par meter on the White LED


Par meter on the Coolwhite LED


Heres a pictures of the LED and the setup.  I have one that has been modified based on the spreadsheet above.  The second unit is a factory unit.

20180701_084111 20180701_085135

20180701_085225 20180701_084101


I measured the light from the bottom to the ground which is 23″ (22″ to the top of the sensor sitting on the floor).  I will also be running a test at around 14″.

Get your Mars Aqua here:

Here’s a picture of the factory light with the blue channel on, white channel on, then both channel on.

20180701_085628 20180701_085647


Heres the picture of the soldering station.  This process was not hard but it took some time.  I had to use a soldering station like the one here: , and slowly desolder the LED lights one by one. Make sure to take a note of which LED color is which.  It gets confusing after awhile.  I had to put masking tape on the RED LEDs as a reference point.

20180630_230442 20180630_230447

20180630_230454 20180630_230458

20180701_000913 20180701_000915

I replace the LEDs with the ones below.  Make sure to get the right amount.  I had to double what I was getting for one unit because I was going set this up for two Mars Aqua light.

Make sure to get the 3 watt LED without it being soldered to a pcb. It should just be a white base with 2 leads on it.  These are the LEDs you’ll need.





If you are looking for different LED options, click on this link: You have the option to get LED in these color range:


Get your Mars Aqua here:

The reason for replacing the LED is to shift the color more into the 15000k-25000k range.  I did not like the warm white or white LED because they were too warm for my taste.  This was for me as I like viewing corals in the 15000K+ range.  Corals in general needs a specific spectrum to thrive which includes the 395nm and 425nm that was missing.  The factory setup already had the 450nm and 460nm so I only replaces a few to get the 395nm and 425nm in on the blue channel.  Here is the light after the modification.

20180701_085701 20180701_085737


It is day and night difference for me.

Here’s a comparison between the two lights

Blue Channel on Max.  Modified vs Factory.  Some of the 460nm were replaced with the 425nm and 395nm, a total of 8 LEDs replaced. It does look a bit less blue but the PAR level is still high.

20180701_152333 20180701_152414

Here is the white channel on max. You can really tell the difference here.  The factory has a natural sunlight white look to it.  Reminds me of my office.  For the most part, I would never really run my lights at this spectrum so that is why it was modified.  The modified one still looks white but it has a hue of blue/purple to it.  I suspect the kelvin rating to be in the 16-18k range with the mixture of the red, green, 10000k and 20000k LEDs.

20180701_152344 20180701_152423

Here is a top view.

20180701_092106 20180701_092059

In these two pictures, we can see that both channel is on at max intensity.  The modified version has a bit more blue while the factory unit has more of a purple hue.  The modified version has more of a deeper blue look because of the much cooler higher kelvin LEDs in the daylight channel which boost the blues.

20180701_152355 20180701_152434

Next we’ll take a look at PAR reading for both lighs

PAR Reading
Factory LED Modified LED
14in 22in 14in 22in
Low Blue Channel missing 59 92 62
High Blue Channel 643 451 608 410
Low White Channel 69 49 73 49
High White Channel 477 338 475 323
Both on Low 155 108 165 missing
Both on High 1111 788 1082 732

Based on the chart above, PAR was sacrificed in order to get the color spectrum that was desired however it is still a lot of light to grow any SPS.

Here are the PAR measurement for the stock Mars Aqua light at 14in and 22in.  Click on each photo and the name of the photo will mention if it’s a blue channel, at 14in or 22in or a mixture of both channel from the URL address.

stock-22in-lowwhite stock-22in-lowbluewhite stock-22in-lowblue stock-22in-highwhite

stock-22in-highbluewhite stock-22in-highblue stock-14in-lowwhite stock-14in-lowbluewhite

stock-14in-highwhiteblue stock-14in-highwhite stock-14in-highblue


Here are the PAR readings for the modified version.

mod-14in-highblue mod-14in-highbluewhite mod-14in-highwhite mod-14in-lowblue

mod-14in-lowbluewhite mod-14in-lowwhite mod-22in-highblue mod-22in-highbluewhite

mod-22in-highwhite mod-22in-lowblue mod-22in-lowwhite


All in all the Mars Aqua is a good light for growing any and all corals. It’s well built with a metal frame which will be sturdier than the it’s competitor at 1/4 the price. If you are looking for a deal, this is it.

If you are interested in a Mars Aqua, you can get one here:

Come back to check out the apex modification on these lights.

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11 thoughts on “Mars Aqua 300 watt LED modification

  1. Hey there, I came across your post as I’m trying to repair my MarsAqua 300w unit. Due to a skimmer malfunction, it pumped my light bar full of water and corroded off most of what I can guess are resistors next to the LEDs. Would you be willing to discuss these lights and how they work at length? If so, drop me an email. I’d much rather solder on new components than buy a new unit.

    Thanks in advance!

  2. Honestly I don’t know what diode they put in there and I no longer have this light so I cannot check, unfortunately.

  3. Hi, thank you a lot for this post, it’s pretty useful to me, I am fixing my mars aqua lamp, I need replace a zener diode above the leds, do you know the zener diode reference? Thank you!

  4. Hi
    My tank is 5″ feet tank in Marine tank I need in lighting my tank pls who much of the cast in Indian rupees…

    Thank & regards
    R Sambasivarao.

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