LUX vs PAR question??

[oreo54]

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Light Meter (Lux & Foot-Candles)

Monitor visible light levels anywhere with fast, stable and accurate response. Results are easily read on the extra large LCD (1½" high, 38.1 mm) with bar graph, low battery and over range indications. The color and cosine corrected sensor meets C.I.E. photopic spectrum. Will read LED light...

www.sperdirect.com

One I bought was an INS DX-200 for $20-ish used..

Welcome INS Enterprise-Lux meter

 

[Reesj]

https://www.apogeeinstruments.com/conversion-ppfd-to-lux/
Dividing LUX by 60 to 70 is pretty standard..

You would think it gets tricky w/ sooo much blue but for some reason..isn't so bad..

This is false for reef lights btw. From my experience and reading, its is more like 30-40 (Even low as 15) not 60-70. 60-70 is whtie light not our more bluer reef lights. Higher the blue in your reef light lowerst the conversion number..

 

[oreo54]

 

[Reesj]

Yes and almost all those high values are from daylight lamps with low kelvin rating. Anything over 14000K LED and we would be looking at conversion rates below 40.

 

[oreo54]

Yes and almost all those high values are from daylight lamps with low kelvin rating. Anything over 14000K LED and we would be looking at conversion rates below 40.

Pretty sure Radium "blue" is the "20000K" bulb.. 51

Curious, have you done your own measurements or have others documentation?
I have to rely on others atm.

I think what you say is reasonable as one calculator gives pure blue LEDs this:

1000LUX = 115.55 "PAR" (really PPFD) Divide by 8.6

Def need to drop things a bit though, as I said others w/ past measurements used 60 for some lights..

One of the problems is some LUX meters just use the natural rolloff of the photodiode.
Others add the green filter..
think some have a sloppy blue side..

 

[Hallowhead]

Anyone find a better conversion for LEDs

 

[Freenow54]

You can use a LUX meter and convert it to PAR. I do not know of any LUX meters will go under the water, though.

Both are equally good and worthless at the same time. Both only capture parts of the visible spectrum and corals use waves below and above what we can see. However, either can be a good guide when used with other things like spectrum charts and stuff so that you can normalize for the testing/reading difficulties.

Some of the common PAR meters are Apogee 210, Apogee 510/520 and Seneye. They are more than a normal LUX meter that is around $20-25.

I spent a lot of time trying to be able to convert Lux to Par. It is apples to oranges not the same better info in other posts. Especially the range into reds and blues. A submersible PAR meter is a must to map all areas of your aquascape. See a BRS ( Bulk Reef Supply ) video where they cover all aspects

 

[J1a]

It's definately a fair point here.

Based on this spectral measurement for my day time light, the PAR (PPFD) is 947, while the lux is 21.06k. It's a factor of 22.

You can imagine when the light shift to actinics, the factor is going to get even lower.

 

[Freenow54]

To Dave Splain Looking at Apogee site this morning. It not only describes the meters, and light function ( PAR ). But also has some interesting links to more information that you should read.