Help interpret PAR values

[AFHokie]

Finally found an LFS where I was able to rent a PAR meter. I did a test at my current settings of 68% and another at 90% and there’s some things that are confusing me.

My best guess is that the angle of the lights and reflection from the glass is causing the odd values. The biggest thing that I was not expecting was the high value at the lower left by the bam-bams. It makes tons of sense though because as my lights have been ramping up they have been acting odd. Closing up in the afternoon and a polyp or two from the very top have melted.

The max values at the top are also lower than I was expecting based on BRS videos. I think some of this is due to surface agitation (right of tank has most). Angle of light could also be at play here. In general, many places drop in PAR as I go higher.

Overall it’s a bit disappointing as I was hoping I could easily support most SPS with such a small tank.

Tank: Lifegard 24. 24x15x15 (approx)
Light: XR15 G5 Pro

68%


90%

 

[Matt L]

Looks pretty good to me. You have plenty of par and spread for sps.

 

[AFHokie]

Looks pretty good to me. You have plenty of par and spread for sps.

I am successfully keeping leptoseris and a psammacora but for any acros, stylos, montis, etc. don’t I need 250+ as a minimum? I get not quite that at the highest point on the center column.

 

[Uncle99]

Maybe some acros, but Monti would do fine in the first pic.
In fact, all those numbers in the 68% look good to me.

Acros will grow upwards towards the light so your 180 at the rock will be much higher as you get closer to the top.

 

[oreo54]

I am successfully keeping leptoseris and a psammacora but for any acros, stylos, montis, etc. don’t I need 250+ as a minimum? I get not quite that at the highest point on the center column.

Part of it..just part.

Effects of various aquarium covers on light transmission

I got a private message from GaryE and thought my reply might be of interest to others. Here’s the message: I know you have done innumerable studies on the various different lighting packages available. Have you ever studied the effects of different coverings on PAR levels? Specifically, I'm...

www.reef2reef.com

BRS never uses covers.

 

[Matt L]

I am successfully keeping leptoseris and a psammacora but for any acros, stylos, montis, etc. don’t I need 250+ as a minimum? I get not quite that at the highest point on the center column.

I keep montis in 100 (bottom of tank) and acros in 200 (top of tank) par. They require high flow too.

 

[AFHokie]

Part of it..just part.

Effects of various aquarium covers on light transmission

I got a private message from GaryE and thought my reply might be of interest to others. Here’s the message: I know you have done innumerable studies on the various different lighting packages available. Have you ever studied the effects of different coverings on PAR levels? Specifically, I'm...

www.reef2reef.com

BRS never uses covers.

First, do you mean lighting is just part of keeping SPS? If so, yes, I know that.

Second, I measured without a cover and the BRS video on the XR15 diffuser shows PAR in the 300s in the center at 6” deep. Same mounting height. Not sure if they have still water or not.

 

[AFHokie]

I keep montis in 100 (bottom of tank) and acros in 200 (top of tank) par. They require high flow too.

Amazing tank. If that is 100-200 PAR you just made me a much happier man.

 

[AFHokie]

So am I right in guessing that the areas where it’s actually less PAR up higher due to the angle of light and glass reflection on the inside glass? It’s almost as if I have shaded spots midway up the tank but there is nothing shadowing those areas.