You still have strains that will want 800 or 1000 allsoo you have rooms with more co2 and less soo the 15% mistake is nothing since still you will not know your max.
I think of it more like am i at 600 or 1000 usefull,but maxing is allways trial and error
I agree there's a lot of variance in strains and the goal should be to get the grow to its light saturation point. My opinion is that growers won't get to the LSP because they're afraid of damaging their plants. Instead, the number on the dial is a convenient way to "optimize" their grow.
The reason I recommend Photone under only very specific circumstances is first, that it requires a paper strip around the phone and, second, that the user has no idea that it might be very inaccurate. Many growers do not use the diffuser so their readings are highly inaccurate. Even if the paper strip is used, there's no way to know if it's accurate.
In contrast, for $32, you can get a product that is, in practical terms, as accurate as a $600 PAR meter.
Turning that around, you can get a number $5 (plus $1,000 for an iPhone) or get valid numbers for $32. I'd spend the extra $27 and "remove all doubt".
Having said that, these instruments should be use to "adjust fire" (I'm a former artillery officer) so a grower should be using the meter to get light levels up to about 800-1000µmol and then watching to see how the plants handle it.
Emphasis on "should be" and that's the punch line. My impression, from being on three cannabis sites, is that, if growers are aware of "PPFD" (most aren't) they are, for the most part, following the advice of sites light growlightmeter.com and are
very hesitant to get their grows to 800, much less to the light saturation point.
This has been a topic of interest (hobby horse?) for me since I started growing in early 2021 and growers are gradually coming around to focusing on light (pardon the pun)*.
Three years ago, the mantra was "nutes, nutes, nutes" and my impression is that the body of growers is starting to accept that it's all the same 18 chemicals and more≠better. Over that time period, the cost of grow lighting has plummeted and there's more research available so growers are starting to get interested in the topic of grow lighting. It still takes time for the herd to follow a different path and my sense is that the body of growers will trust the number on the meter as being the destination rather than using it as a guide.
To your point, it should be a means to an end (move it toward 1k on the meter and see how the plants react) but I do sincerely believe that measuring light is so new that it is still an end in itself and there's a hard stop when that number is "too high".
Just my tuppence and I very much appreciate your perspective.
*RIU seems to be changing the most rapidly; another site that I'm on, the one with the police call sign in the name which is where I have my grow diaries, seems to be pretty well set in their ways; and the site for autoflowers, which I don't frequent much any more, is (was) similar to RIU in how the growers adopt technology.
