Phone app as a par meter thats pretty sweet

[nightmarepl]

Underwater PAR Measurements for Reef Aquariums

The entire reef ecosystem depends on light for photosynthesis, which is measured as photosynthetically active radiation (PAR). But without correction, PAR meters calibrated in air provide only relative values underwater. This article explains how to take accurate PAR measurements underwater.

growlightmeter.com

 

[MadReefer]

Underwater PAR Measurements for Reef Aquariums

The entire reef ecosystem depends on light for photosynthesis, which is measured as photosynthetically active radiation (PAR). But without correction, PAR meters calibrated in air provide only relative values underwater. This article explains how to take accurate PAR measurements underwater.

growlightmeter.com

I have seen similar on other sites but no thanks. I use Lux Meter and place it just above the water level and get about 18,500 lux.
Be sure the screen is clean as even finger prints will give an incorrect reading.

 

[Juano908]

I've tried using a Lux Meter and this is what I'm getting using AquaticLife T5 hybrid with Radion XR30 G4 running Coralab AB+ at 70% intensity.
Definitely something is not right.

 

[MadReefer]

I've tried using a Lux Meter and this is what I'm getting using AquaticLife T5 hybrid with Radion XR30 G4 running Coralab AB+ at 70% intensity.
Definitely something is not right.

I agree. The 1st app I used did the same so switched to a different one. Not familiar with an actual Lux Meter though.