I don’t have the details on PPFD, nor a meter to measure it, I just used a LUX meter and a conversion factor - but its very unlikely that it exceeded 400. I agree with @Adamsmasherz about nutrition being more important - I think the reason I had so many blooms is because I likely over fertilized and stressed the plants.
@Pierre Sorry I missed your question.
Here are some details on my build:
https://ledgardener.com/forum/viewtopic.php?p=3873#p3873
These days I’m using 6 x 22" strips (F-series 22" F562B 4000K) running at ~90% max current (powered with a HLG-240H-24A) and hanging 8-10" above the plants for a 8x2’ growing area. But I mainly use this for starting seeds and keeping my Meyer lemon alive during winter.