PAR during lighting switch

[TheSheff]

Hello, I am going to be switching from (2) T5's + (2) Kessil A160's to (3) Quanta Pro LED Bars and I am working on how I am going to keep the PAR as close to the same as possible. PAR Meters are very expensive and I cannot find anyone that would let me borrow their meter, so couldn't I theoretically use a cheaper PAR Meter from amazon even if it is not accurate and make sure that number is the same with the new lighting, since I already know my corals are acclimated to this current PAR? Hopefully this makes sense. Thank you!

 

[Mr. Mojo Rising]

do you have LFS's in your area? Many of them rent the PAR meter, check with them.

Another method is the iphone par meter, I think it costs a few dollars and not 100% accurate, but good enough to give you good idea.

 

[TheSheff]

do you have LFS's in your area? Many of them rent the PAR meter, check with them.

Another method is the iphone par meter, I think it costs a few dollars and not 100% accurate, but good enough to give you good idea.

None of the LFS's are willing to do that lol. Do you agree that I dont necessarily have to measure "par" as long as the number is the same when I switch lights? What about this meter? https://shorturl.at/fgPX4

 

[oreo54]

None of the LFS's are willing to do that lol. Do you agree that I dont necessarily have to measure "par" as long as the number is the same when I switch lights? What about this meter? https://shorturl.at/fgPX4

Well sort of.
Here is the issue, when using a lux meter if the light spectrums are very different you have a problem.
A heavy blue light and say a 6500k daylight light may have the same lux but very different par. The blue heavy light will have much higher par even though they've the same lux measurements as a white heavy light.
This pic shows various lux meters and their spectral response.

It’s Not All Sparkle. It’s Spectrum and Cosine Correction: Your Guide to Buying a Light Meter - kW Engineering | Sustainable Buildings & Energy Efficiency Consulting

In a previous post, I wrote about smartphone apps and their inadequacy with respect to illuminance measurements (that is, their ability to measure footcandles or lux). That post took a deep dive into why smartphones are not up to snuff as a professional light meter. As I wrote that post I...

kw-engineering.com

Then there is a matter of how different lights disperse the light. Wider? Narrower?

So I agree that you could but it isn't easy.

The BRS " rental" program isn't too expensive

 

[Idech]

None of the LFS's are willing to do that lol. Do you agree that I dont necessarily have to measure "par" as long as the number is the same when I switch lights? What about this meter? https://shorturl.at/fgPX4

Get the photone App and a waterproof case for your phone on Amazon. There is a Youtube guy who tested it and it came extremely close to an apogee results.

This will cost you 20$.