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Surface Agitation vs PAR

Maximitsurugi

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Hey @Dana whats up. I have a question for you and the R2R team. I wonder how much surface agitation affects PAR reaching my corals.

For example, I use my seneye PAR meter to get a range of 300-320 on X sps while flow is off. I then turn my flow on. I keep my surface like a raging river. When i look at the numbers with the meter still running, the PAR hops around a ton and goes even as low as 150 depending.

Am i short changing my corals' DLI and growth by having such an active surface with such random, often lower PAR values?
 

Pistondog

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Hey @Dana whats up. I have a question for you and the R2R team. I wonder how much surface agitation affects PAR reaching my corals.

For example, I use my seneye PAR meter to get a range of 300-320 on X sps while flow is off. I then turn my flow on. I keep my surface like a raging river. When i look at the numbers with the meter still running, the PAR hops around a ton and goes even as low as 150 depending.

Am i short changing my corals' DLI and growth by having such an active surface with such random, often lower PAR values?
Wait for the experts, but id say the water surface is like an active diffusion lens. Not reducing the light total, but dispersing it differently.
To contradict, some might be reflected out of the tank, depending on wave amplitude, and light angle of incident.
If there are light shows on the walls only when surface is active, then your corals are not getting this light.
 

The0wn4g3

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Hey @Dana whats up. I have a question for you and the R2R team. I wonder how much surface agitation affects PAR reaching my corals.

For example, I use my seneye PAR meter to get a range of 300-320 on X sps while flow is off. I then turn my flow on. I keep my surface like a raging river. When i look at the numbers with the meter still running, the PAR hops around a ton and goes even as low as 150 depending.

Am i short changing my corals' DLI and growth by having such an active surface with such random, often lower PAR values?
Anecdotal, but I placed a PAR Meter in my tank and pumps off it read 318-320, pumps on it read 215-320. So the max reading was consistent but depending on the flow, it dropped over 100 and bounced all over the place.
Sounds consistent with your results, and my surface agitation is not significant.
 
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Maximitsurugi

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Anecdotal, but I placed a PAR Meter in my tank and pumps off it read 318-320, pumps on it read 215-320. So the max reading was consistent but depending on the flow, it dropped over 100 and bounced all over the place.
Sounds consistent with your results, and my surface agitation is not significant.

And im guessing that it all comes down to how much agitation is present as well. Right?
 

Dana Riddle

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How did I miss this? The lensing effect of waves can focus or de-focus light. There are peer-reviewed reports that light intensity can double due to lensing. However, waves in home aquaria cannot duplicate this effect.
Here's an experiment I did when in Hawaii:
 

blasterman

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Surface agitation reduces PAR. How much is tricky without some pretty advanced lighting algorithms, although you might be able to simulate it with a ray tracing program.

Ripples of water refract light in angles more extreme than if the water is at rest, so there's 'X' time light rays are being focused and bounced at walls, floor, etc due to the angles of the ripples that don't exist with smooth water. If PAR is 320 while the water is at rest, and goes up and down when there's agitation then it's obvious you are losing energy via lighting the surrounding room.

However, lots of agitation increases gas transfer and increases water column uniformity. It also helps blend hot spots and focus points with existing lighting (excluding really diffuse light sources like T5, etc). So, at least in my opinion any trivial PAR loss due to shimmer is gained back via other factors.
 

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