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

 

[Roughneck]

@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.

Hi,

I'm having similar issues with my XR30 Gen6 on my Red Sea 200. To get 220-230 Par on the top of my rockscape (for SPS) it gives me 180-200 Par on the sand bed (@60% on AB+). I really want some Scolys and Trachyphyllias on the sand bed wich like lower Par.

Have you done a Par mapping after the Narrow Lens kit?

Thanks for the help

 

[RWReefer]

Hi,

I'm having similar issues with my XR30 Gen6 on my Red Sea 200. To get 220-230 Par on the top of my rockscape (for SPS) it gives me 180-200 Par on the sand bed (@60% on AB+). I really want some Scolys and Trachyphyllias on the sand bed wich like lower Par.

Have you done a Par mapping after the Narrow Lens kit?

Thanks for the help

Yep. After changing to narrow lens got the expected top down reduction in PAR. I’ll have to find the file for numbers, but if I recall it was like 250 on top, 100 on the sand where I was getting nearly 225 on the sand.

 

[Roughneck]

Yep. After changing to narrow lens got the expected top down reduction in PAR. I’ll have to find the file for numbers, but if I recall it was like 250 on top, 100 on the sand where I was getting nearly 225 on the sand.

Sweet that's exactly what I'm looking for. I just ordered the Lens kit. That crazy spread would be amazing for a SPS dominant tank, just not so much for a mix reef.

 

[RWReefer]

@Roughneck

Before narrow lens

After narrow lens

 

[Roughneck]

@Roughneck

Before narrow lens

After narrow lens

That makes way more sense for a mixed reef. Thanks for the pics.

 

[BeanAnimal]

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.

What does it matter? The numbers are fairly meaningless in most contexts anyway.

Yes, the glass, rock and sand reflect light. The effect will be lesser as the rock changes color.

"flow on or off" - not that PAR measurements mean anything anyway, but why bother measuring anything with flow off if the coral don't live with flow off?

 

[BeanAnimal]

@RedReefer -
Not sure what is funny, but happy to discuss.

@Roughneck - I did not see your last post above prior to responding. But as you have found out the narrow lens changes the angle of light and less is reflecting off of the glass and is now more concentrated directly under the lenses. Do consider that as the tank fills out, those reflections form the "wide" lens will lessen and with the "narrow" lens shadowing under growing corals will be increased.

You have stumbled on one of the only viable uses for the "PAR Meter" in that it can show you relative light levels as you make changes. The point was that the actual numbers are rather meaningless in context to "coral" needs, health or growth or comparing to other systems. There are just far too many variables in spectrum, meters, measurements, etc.

 

[RWReefer]

Thanks for everyone’s help in resolving this issue. Got the exact result I was looking for!