What is going on with my PAR?

[RWReefer]

@vetteguy53081 @Lavey29 @oreo54

Did some additional investigation.

Raising lights, no change in distribution. Removing light shade, no change in distribution. Orienting lights vertical vs horizontal, no change in distribution.

BUT, I came back to reflection and when I put my hand on the front panel of the tank, between the PAR meter and the front wall, I get the numbers I would expect to see (PAR at 130 on the sand).

So this leaves 2 scenarios.

1) The reflection of the light off the aquascape/glass is causing the PAR at the front of the tank to spike.

2) the reflection is causing the PAR meter to misread the actual PAR.

Thoughts on the most likely scenario? I don’t see the reflection raising PAR coming up anywhere as an issue on this forum, so that leads me to scenario 2.

 

[vetteguy53081]

@vetteguy53081 @Lavey29 @oreo54

Did some additional investigation.

Raising lights, no change in distribution. Removing light shade, no change in distribution. Orienting lights vertical vs horizontal, no change in distribution.

BUT, I came back to reflection and when I put my hand on the front panel of the tank, between the PAR meter and the front wall, I get the numbers I would expect to see (PAR at 130 on the sand).

So this leaves 2 scenarios.

1) The reflection of the light off the aquascape/glass is causing the PAR at the front of the tank to spike.

2) the reflection is causing the PAR meter to misread the actual PAR.

Thoughts on the most likely scenario? I don’t see the reflection raising PAR coming up anywhere as an issue on this forum, so that leads me to scenario 2.

I too believe reflection.

 

[oreo54]

So I considered the shade and confirmed that I get similar results both with and without the shade. I will have to try and mock a mount up to raise the height.

Putting your hand on the glass is much like painting it black. You lose the glass air gap that causes the back reflection (or some such voodoo). You can get the replacement narrow lenses so as to decrease the front/back spread. PAR may end up more even but less unbalanced top to bottom..

1) The reflection of the light off the aquascape/glass is causing the PAR at the front of the tank to spike.

That was always the scenario. You are also getting some off the bare rock....imho
You lost most of the glass reflection by painting the back black.

Technically the max height of a g6 is actually too high for the wide spread (126.3 degrees according to Radion).

The beam angle right out of the light measures 126° which creates the most even and widest spread of light from a Radion LED to date.

For fun and if you got a glass top.. try 6" lens face to water surface. That covers a 24" dia cone.
At 9" every led is throwing a 35.5" dia cone of light. Roughly of course.
That will probably screw up the l/r spread a bit.

BTW what are your tank dimensions?

And *technically* if you are going for an even spread you should have the center distance between the 2 lights wider. Spread em apart about 2 inches.

 

[RWReefer]

Putting your hand on the glass is much like painting it black. You lose the glass air gap that causes the back reflection (or some such voodoo). You can get the replacement narrow lenses so as to decrease the front/back spread. PAR may end up more even but less unbalanced top to bottom..


That was always the scenario. You are also getting some off the bare rock....imho
You lost most of the glass reflection by painting the back black.

Technically the max height of a g6 is actually too high for the wide spread (126.3 degrees according to Radion).



For fun and if you got a glass top.. try 6" lens face to water surface. That covers a 24" dia cone.
At 9" every led is throwing a 35.5" dia cone of light. Roughly of course.
That will probably screw up the l/r spread a bit.

BTW what are your tank dimensions?

And *technically* if you are going for an even spread you should have the center distance between the 2 lights wider. Spread em apart about 2 inches.

Tank is 47” x 20” x 22” H.

You’re all over it though with the light height. If I lower the lights down to about 6” off the water level, I get the expected drop from top to bottom of the tank.

I’ve already got a custom lid for the tank, so I’m going to need to pursue to route of shorter mounts.

 

[Lavey29]

And that is the million dollar question. What are you running on your set up and what’s the light to water distance?

XR15 lights on standard RMS 8 inch mounts. I run them at 100% intensity on AB plus setting. My red sea tank is 36x22x22. I get 350 par on top, 175 to 250 mid tank, 75 to 125 bottom.

 

[Hooz]

Yes. They touted the spread of the G6, and it sacrificed some direct PAR for the sake of spread (and reflection). If you want a more "standard" PAR distribution then, yes, get the high intensity lens. It's not actually "high intensity", it just directs the light more like the G5 did.

 

[RWReefer]

Yes. They touted the spread of the G6, and it sacrificed some direct PAR for the sake of spread (and reflection). If you want a more "standard" PAR distribution then, yes, get the high intensity lens. It's not actually "high intensity", it just directs the light more like the G5 did.

Got longer screws to mount the radion closer to the water and a couple of the narrow lens kits on the way. I have a feeling I’m not going to like the look of the longer screws so hopefully the narrow lens kit solves the issue. Appreciate you chiming in.

 

[BeanAnimal]

Did you have all flow off when you par checked?

Ignoring the (lack of) meaning of the value... Coral live with the flow on so I am not sure why measuring "PAR" in any other condition has much value in this context.

 

[RWReefer]

@Hooz @Lavey29 @oreo54 @vetteguy53081

Got this resolved. Narrow lens on the radion fixed the issue. Appreciate all the insight and help in dissecting the issue. Still need to map it and dial in, but first readings on the PAR meter showed 150 on top down to 50-90 on the sand bed showing a more expected distribution of PAR lower in the tank. No more “hot spots” on the front display or randomly throughout the scape.

 

[Solo McReefer]

You have a tank cover

That's blocking a lot of PAR

Diffusers block a lot of PAR too

Surface agitation blocks PAR

I didn't read anything, just looking at the picture. Those three things explain your low PAR readings, mostly

 

[vetteguy53081]

@Hooz @Lavey29 @oreo54 @vetteguy53081

Got this resolved. Narrow lens on the radion fixed the issue. Appreciate all the insight and help in dissecting the issue. Still need to map it and dial in, but first readings on the PAR meter showed 150 on top down to 50-90 on the sand bed showing a more expected distribution of lowering PAR lower in the tank. No more “hot spots” on the front display or randomly throughout the scape.

Great to hear