Two Hydra 26HD with significantly different PAR measurements

trmiv · Jul 12, 2019

I rented an Apogee 520 from BRS to test the par on my tank. I have two Hydra 26 HD’s that came with my Reefer 350 Deluxe. They’ve both been on the tank since March. You can see from the pic that the Parent on the right of the pic has significantly higher par at the surface than the child on the left, and this continues under water in roughly similar spots with the parent having 100-200 more par in various areas.

Anyone have any idea why this would be? I tried loading various saved schedules to see if it would change and it never does.

Crabs McJones · Jul 12, 2019

When you look at the pucks, is there a noticeable difference in light output? Like maybe one has an LED out of it or something?

trmiv · Jul 12, 2019

So I ended up doing multiple tests

1)set each light as a Parent of their own tank. Result was the PAR was just about the same on both with the lights at the same setting.

2)set them back up Parent/Child of one tank. Result was the right one had 200-400 more PAR depending on what intensity I tested.

3)Again set each as a Parent of their own tank. Result was they again had roughly equal par on the same settings.

So it seems when set as Parent/Child the right one always has 200-400 more par than the left. When set with both as Parents then they are both roughly the same PAR.

I contacted AI about this and they are sending me a new light to test.

Saltyreef · Jul 12, 2019

I would reach out to aqua illumination. They have pretty good customer service. It could be something internal not driving the leds correctly. See what they say. Are the diffused lens' installed in each fixture correctly? And are they the same degree angle? Should look like a somewhat frosted lens. AI sells different degree lens' and may have gotten mixed in at the factory if you havent messed with them.

Saltyreef · Jul 12, 2019

I wonder if thats normal. I have two 26 non hds and im curious now!

alton · Jul 12, 2019

PAR Meters are worth their weight in Gold!

trmiv · Jul 12, 2019

I’m debating buying a Seneye now so I always have a PAR meter to test stuff like this with as well as helping with coral placement. This new tank is my first major experience with LEDs. Up until last year I was still using halides!

blstravler · Jul 15, 2019

Can I ask how far off the water you have your lights? I did par readings today on my HD 52’s and your readings are higher then mine. Maybe you have the setting up higher?

trmiv · Jul 15, 2019

The standard Red Sea mounts put them 10” above the water line

nden · Jul 15, 2019

I actually noticed the same thing when measuring my Prime HDs with a lux meter. Just above the waterline, the lux reading is much higher when under the right light which is set to child. I chalked it up to the way I have the lights angled. Though when I put the meter about an inch from the light puck itself, they read about the same. If you still have the lights, maybe try doing that?

blstravler · Jul 15, 2019

trmiv said:
The standard Red Sea mounts put them 10” above the water line

How far from the light was your 500 reading?

trmiv · Jul 16, 2019

I believe that was 5-6” under the water. I took that big rock down because the Par on it was too high for anything I want to keep so I can’t measure that specifically again.

trmiv · Jul 22, 2019

So update. Got the new light today. Turns out the one that is the wrong one was the light with the HIGHER par. The new light matches the one on the left that had the lower par numbers. So I’m sending back the right one that had more par. Support thinks maybe an extra cool white was added or something.