What is going on with my PAR?

[RWReefer]

Below is a snapshot of my PAR readings. Running two XR30 G6 Pros at the following:

Point Intensity: 75%
UV: 100%
Violet: 100%
Royal Blue: 100%
Blue: 100%
Green: 24%
Red: 24%
Warm White: 35%
Cool White: 35%

PAR on the front of the tank is all over the place. Back of the tank gives me expected values at sand (100-130 and slowly getting higher as I trend up.

Could this all be from glass reflection? Windows were shaded when I took the PAR measurements so room was not lit. I'm stumped.

 

[oreo54]

Below is a snapshot of my PAR readings. Running two XR30 G6 Pros at the following:

Point Intensity: 75%
UV: 100%
Violet: 100%
Royal Blue: 100%
Blue: 100%
Green: 24%
Red: 24%
Warm White: 35%
Cool White: 35%

PAR on the front of the tank is all over the place. Back of the tank gives me expected values at sand (100-130 and slowly getting higher as I trend up.

Could this all be from glass reflection? Windows were shaded when I took the PAR measurements so room was not lit. I'm stumped.

Is the back glass painted?

 

[Lavey29]

Did you have all flow off when you par checked?

 

[RWReefer]

Is the back glass painted?

Yes, back of the tank in black. That’s what led to towards believing it had something to do with reflection.

 

[RWReefer]

Did you have all flow off when you par checked?

I did. Powerheads and return were off to take measurements.

 

[oreo54]

Yes, back of the tank in black. That’s what led to towards believing it had something to do with reflection.

Painting the glass dark color kills par. You lose the reflections you are getting in the front of the tank and obviously losing par.
BRS did a "study" on this.
Another before them also.
It's weird physics..

 

[RWReefer]

Painting the glass dark color kills par. You lose the reflections you are getting in the front of the tank and obviously losing par.
BRS did a "study" on this.
Another before them also.
It's weird physics..

Oh I’m all on board I’m with black absorbing light. The issue I am seeing is PAR values near my sand bed that are higher than the top of my aquascape. That seems off to me and sort of handcuffs my plan for a mixed reef setup.

 

[Lavey29]

Oh I’m all on board I’m with black absorbing light. The issue I am seeing is PAR values near my sand bed that are higher than the top of my aquascape. That seems off to me and sort of handcuffs my plan for a mixed reef setup.

What is the width of the tank? Do you have lights spread equally across the top on standard 8 inch mounts?

I use XR15 lights on my mixed reef.

 

[vetteguy53081]

Below is a snapshot of my PAR readings. Running two XR30 G6 Pros at the following:

Point Intensity: 75%
UV: 100%
Violet: 100%
Royal Blue: 100%
Blue: 100%
Green: 24%
Red: 24%
Warm White: 35%
Cool White: 35%

PAR on the front of the tank is all over the place. Back of the tank gives me expected values at sand (100-130 and slowly getting higher as I trend up.

Could this all be from glass reflection? Windows were shaded when I took the PAR measurements so room was not lit. I'm stumped.

How high do you have lights above water surface?

 

[bubbgee]

Oh I’m all on board I’m with black absorbing light. The issue I am seeing is PAR values near my sand bed that are higher than the top of my aquascape. That seems off to me and sort of handcuffs my plan for a mixed reef setup.

Maybe the sand is reflecting the light up? Never heard of it but that's the only thing i can think of...
Otherwise, borrow someone else's par meter?

 

[RWReefer]

What is the width of the tank? Do you have lights spread equally across the top on standard 8 inch mounts?

I use XR15 lights on my mixed reef.

Tank is 47" wide. Lights are mounted width horizontal with the tank front on the standard RMS mounts, approximately 13" centered from each side.

 

[RWReefer]

How high do you have lights above water surface?

Lights are on the RMS mount, 8" above water surface.

 

[Lavey29]

Lights are on the RMS mount, 8" above water surface.

Maybe those aftermarket light shades are causing different specs and par numbers?

 

[RWReefer]

Vetted that already and determined no noticeable change with or without the shades. Also confirmed that PAR values raise or lower in unison when I increase or decrease the light intensity. I feel like this is a pretty basic setup so that’s why I am thoroughly confused lol.

Maybe those aftermarket light shades are causing different specs and par numbers?

 

[Lavey29]

Vetted that already and determined no noticeable change with or without the shades. Also confirmed that PAR values raise or lower in unison when I increase or decrease the light intensity. I feel like this is a pretty basic setup so that’s why I am thoroughly confused lol.

Well your rockscape is similar to mine and I get varied numbers around the tank to but there is a noticeable rise from the sandbed to the top of the rocks. What par meter did you use? Was it calibrated properly?

 

[RWReefer]

Well your rockscape is similar to mine and I get varied numbers around the tank to but there is a noticeable rise from the sandbed to the top of the rocks. What par meter did you use? Was it calibrated properly?

It is being borrowed from a generous reefer here on the forum (@14 foot reef).

Not sure date of last calibration, but what seems amiss is that I see the expected PAR reduction on the backside of the rock work. Lights are centered directly above the scape, so they only thing that makes any logical sense to me would be reflection causing the spike in PAR at the bottom, but I don’t know enough about aquariums to have confidence in that assessment.

 

[vetteguy53081]

Lights are on the RMS mount, 8" above water surface.

Shades may post an issue and are you able to raise it 2 inches?

 

[Lavey29]

It is being borrowed from a generous reefer here on the forum (@14 foot reef).

Not sure date of last calibration, but what seems amiss is that I see the expected PAR reduction on the backside of the rock work. Lights are centered directly above the scape, so they only thing that makes any logical sense to me would be reflection causing the spike in PAR at the bottom, but I don’t know enough about aquariums to have confidence in that assessment.

Then why wouldn't I get the same reflection in a similar tank and scape?

 

[RWReefer]

Then why wouldn't I get the same reflection in a similar tank and scape?

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

 

[RWReefer]

Shades may post an issue and are you able to raise it 2 inches?

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.