Using Lux Meters

@dbrn32 I purchased a Light meter and I’m not sure if measuring Lux is even useful for this hobby. Let me know what I need to do.

I don’t use them because they are weighted to green wavelengths. There is supposedly a ballpark conversion factor based on color temp of lights, but I don’t know what it is. Maybe @Aolelon or @1BigFella know?

Yes there is a conversion factor. Are you using the HLG QB’s? They actually have a lux to PPFD calculator on their website. This really only works for the qb288’s though

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Yep. QB 288’s. Thanks for the reply. Glad I didn’t waste my money like I thought I did. Just like to know what my lights are putting out.

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What are you using the 3000k or the 3500k? For 3000k 80CRI the conversion factor for these lights is 69. So you would take you lux and divide my 69… 10000lx/69 = 145umol/s/ . Then if you wanted to get your ppfd you would divide by your area in square meters.

Alternatively the specific conversion number is Samsung 561C 3000K 80 CRI 0.014505. You can multiply your lumens by that and get your umol/j as well. Only works for 3000k though.

If your CCT is higher the conversion will be as well… 3500k 80cri is around 71 and so fourth.

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3000k hlg135

I would just use the 69 conversion factor. You can search online the readings your plant should be getting to really tune in the light.



Awesome, thanks!


And the nice thing, is lux meters are in to $10-$20 range on Amazon. Way cheaper than a PAR meter. In looking at mine with a known spectrum and color filters, I found a peak response in the yellow, not the green. Doesn’t matter much though. Neither one is needed much by plants. Nice to know the conversion factor, though!

I read some things online that say plants can’t use much more than 85000 lux without adding CO2.

I used mine and it read pure insanity

The new quantum boards are growing shizz like crazy. Best purchase to date. Decided to go drink vs put together the 3 rd light. :roll_eyes:

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@Aolelon bookmarked! Thanks for that.

Enjoy responsibly, @Familyman :+1: :beer:


Lmao. Priorities! #winningatlife

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This! I’ve been looking for this!

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What lights are you using? @blackthumbbetty

Hlg 320w 288’s v2

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If you goto HLG website. And you search PPFD. The first blog post that pops up, actually has a calculator for converting lux to ppf for the v2 3000k. Or you can do the math yourself. It’s nice to have as a bookmark either way.

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What is the optimal range for ppfd?

Ppfd average of 800 is rocking pretty good on ambient co2. 600-1000 would be the ideal range for flowering.

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