as far as the light goes, I don’t have a meter to test the efficiency. PPFD I have the pots chart and it’s brand new from the manufacturer (spider farmer) and it draws 750ish watts from the wall. I have it turned up to 60% I will crank them up today to 80%!
750 watts - would love to have that in my 2" x 4'
Spider - oh, yeh, I see the orange end caps. Spider came out with the 7000 enhanced about two years ago and that light has a really nice PPFD map. Is that the light you have?
(checks the Spider site)
Yeh, a big motha'. That light will really crank out the photons so tread carefully. I found their recommendations
here and they're erring on the side of caution - from a yield perspective, max yield comes from getting as much light on the plant as it can handle. Manufacturers will "never" tell you that because there's nothing but risk in saying that - you'll get a good crop at 700µmol (their recommendation for veg) but, if they tell growers to crank it to 1k and they get light burn, Spider will never hear the end of it. That's my theory about it; I don't have any particular knowledge about it but I know that companies that want to stay out of trouble will understate rather than overstate.
Re, a phone app - only if you can calibrate it against a known source. I tested Photone back when it was called Korona and it failed. I tested it again a couple of years ago and it was 16% high. I use an Apogee but I also have owned a couple of Uni-T lux meters. If you can dial in your phone+software and if you want to schlep your phone in a tent and if you don't mind putting on the kludgy little sunshade that Photone requires when using iOS, you can save $27. And then you'll have to recal when you get a new phone.
If you can't tell I don't think much of phone+software, I'm having a bad keyboard day.
A phone+ software can be spot on or it can be very wrong. In contrast, the $32 Uni-T ships with a 5%± variance and, the way I put it, it's as
inaccurate as an Apogee so it will work very, very well for the vast majority of growers. I've attached a document I wrote about converting lux to PPFD. Most lights can use 0.015 and looking at the spectrum for the SE7000, that should do well but 0.0147 might be more accurate since there's a fair amount of blue in the spectrum. Either will get you close enough to start.
Lacking a meter, if you're at 80% power, a hang height of 12" should give you about 720-1020µmol, based on the numbers in their non-CO2 flower recommendation. That's a jump from where you are now so I'd be inclined to start at 16", check the plants, drop to 14", check the plants, etc.
That's the key - we can toss around numbers but it the leaves start to taco or turn side ways so they're turning vertical to the light, then you've gone past their max.
HTH.
