Correct way to measure PAR?

[FrugalReefer]

I have an Apogee 510 and for those also with a PAR meter what is your preferred way for getting a good PAR reading? Specifically, I know the reading will go all over the place due to the water surface agitation and what not and with that being said, is it best to take the lowest measurement, the highest measurement or an average?

 

[Ron Reefman]

First of all, set the pumps to feed mode and the water will smooth out for better readings. Make sure the sensor is pointing at the lights. Just a little move off the direct aim at the light will have a significant effect. Try working with it out in the sun and see how much it changes.

Taking an average seems like a good approach if you can't get a stable reading.

 

[Waters]

I have always taken PAR readings with everything running. I want the number the coral will be receiving which is with surface agitation.....at least that is what I am telling myself lol. I assume surface agitation reduces PAR (and just doesn't affect the reading of the meter?)

 

[NormanB]

I recently watched a BRS video and surface agitation did little to reduce PAR readings.

 

[FrugalReefer]

I have always taken PAR readings with everything running. I want the number the coral will be receiving which is with surface agitation.....at least that is what I am telling myself lol. I assume surface agitation reduces PAR (and just doesn't affect the reading of the meter?)

I agree with you 100%. The corals will be photosynthesizing with all powerheads and the return pump running 99.99% of the time.

 

[rtparty]

Take readings both ways. Surface agitation actually increases PAR in little quick bursts as it focuses the light like a magnifying glass

 

[mike550]

I measure PAR with the powerheads off but my return pump running so I have the correct water level and least amount of surface waves. It‘s important for the sensor to point vertically regardless of where the lights are so you can get a sense of hot spots etc. I don’t really worry about potential changes due to surface waves since they’re random and not standing waves so I figure it evens out over time

 

[oreo54]

About caustic lines....

Glitter Lines: More Than Aesthetic?

This article will present some initial data from recent experiments relating to the physiological effects of glitter lines within aquaria, and also how our artificial glitter compares to that found in natural reefs.

reefs.com

The average PAR value of glitter lines measured over short periods (a minute or two) always very closely equaled the PAR measured when a condition of ‘no glitter’ prevailed. In other words, the average intensity of the light field produced by glitter lines over a few seconds’ time cannot possibly exceed the average light intensity in a ‘no glitter’ condition under the same set of circumstances.