PAR readings

[kamloops_reefer]

Looking for opinions on PAR readings - I just tried out our Seneye device that we've had for over a year (only used for a month). When I place the sensor just above the water (about 10" from light source) I'm pulling about 160 PAR on a relatively large DIY led build.

This seems low? Am I mistaken that I should be getting 300-600 PAR at the high points in my tank (in water)?

To compare, I tested the sensor against another LED light I have at a similar distance, and a dual bulb 48" T5 HO fixture at approximately 12" below (not in water) and they were 160-170 PAR

[ReefMadness]

if i remember correctly the seneye par meter will give accurate measurements of T5 and Halide fixtures but is not very good at picking up led. someone feel free to chime in if you can explain why.

[iamfrontosa]

^ i read that somewhere also.

[Scythanith]

LED readings are usually only about 5-10% off in my experience. Each colour spectrum is different. You can find the articles and proper calculations to adjust an apogee sensor on their website. Not sure about the Seneye though.

I'd say 160 is quite low on the water surface. I get anywhere from 450-800+ at water's surface with Mitras and T5's (about the same height as you).

[Frogger]

Apogee makes a led par meter, although Bulk Reef Supply tested it and said it was calibrated improperly. They may have fixed that poor calibration.

[dcw1sfu]

This may interest you guys. It was a comparison done on the Seneye and Apogee par meters. They were very close for the most part.

http://www.reefcentral.com/forums/showthread.php?t=2626700


Also a BRS TV video comparing the Par Meters:

https://youtu.be/6hUkufXBb3I

[crimper]

Ok I took the time and measured my tanks par today, but before I post all my LED fixture (Evergrow) PAR readings I have a couple questions for you. First, what firmware version are you using? Mine is V2. Second, when measuring PAR did you make sure that the sensor is directly under the light or perpendicular to the light source. The reason for this is you will get slightly different reading when the sensor is not perpendicular to the light source. Seneye Sensor doesn't have cosine correction like other par meters that's why it is imperative that the sensor is perpendicular to the light source when measuring PAR.

So here's what my par levels are: Please note that my light fixture is more than 3 ft above the water level of my tank.

ALL BLUES @ 100%, distance from fixture: ~48"

http://i584.photobucket.com/albums/ss289/mdspugs/parBLUES.png

FULL SPECTRUM (100% Blues; 40 Whites), Distance from fixture ~48"

http://i584.photobucket.com/albums/ss289/mdspugs/parFULL.png

FULL SPECTRUM (100% Blues; 100% Whites), Distance from fixture: 10"

http://i584.photobucket.com/albums/ss289/mdspugs/parFULLSPEC.png

I used to pay too much attention about PAR, I have burnt lots of SPS when I started as I was chasing the PAR readings based on the PAR guidelines on the internet not knowing the correlation between my water nutrients and PAR.

[kamloops_reefer]

I am using V2 as well - I noticed the readings would wander a bit as I tried holding it perpendicular.

my phone has a lux reading - I will compare the two to get a baseline and see if that determines anything.

I know I've had great growth in my tank before on some coarls

[crimper]

You have also mentioned that you took a reading on a dual T5HO with a reading around 170ish @ 12" which is I think is about right. I am getting 300ish on my frag tank 4x TEC T5HO @ 12" considering my bulbs are more than a year old. :redface:

I think your LED emitters are not giving you it's full potential anymore. What I would do is maybe go to a buddy that has LED fixtures and compare his reading to yours using the same PAR meter.