If this is accurate I am giving them way too much light.

Sorry I can't be of help...I keep most of my c&s in a basemet (no natural light) for abt. 6mo (approx. 200 of them); & have been for abt 10yrs. Rest of the time they are outside. I have few CFL bulbs left (min. 23W) & lots of LED tubes sold as grow lights - IIRC they are 24W each. I never checked PPFD...they are closer to the plants, from abt. 4" to max. 16". If any etiolate, I prune them in spring.

No worries. I rearranged the plants, raised the lights as high as they'd go and now levels are much more where (I believe) they should be. I'll keep an eye on em. :o)

Photone isn't very reliable as it isn't cosine corrected like a proper lux meter would be. Get a lux meter. A cheap but good one is $20. A better one is $35. For high CRI value white LEDs you can roughly approximate 70 lux=1ppfd. And even by the app readings, that's not really crazy high. Based on the chart you link, full sun vegetable crops grow at 600+ ppfd. Cacti and succulents are also in the same range of light requirements as full sun vegetable crops. So 700 ppfd is definitely up there, but not ludicrously high. The totem pole definitely needs probably in the range of 800 to actually grow a decent rate and not become super stretched out. The others can handle 500+ ppfd easily.

Thanks, John - very helpful. I will pick up a lux meter and recheck the values with that.

Lx 1010b is what you need at the minimum.

Cool. I ordered this guy. Should be here tomorrow:

https://smile.amazon.com/gp/product/B07LF4BT8V?ref=ppx_pt2_dt_b_prod_image 

To update... Got the meter and did a little adjusting of light fixture heights and plant placement. I now am getting about 800+ppfd at the top of the totem pole cactus, about 550-600 for the Pachypodium, and 180-250 for the shorter plants. I may pick up one more of these fixtures to put in the middle, but first will see how everything does over the next few months. Thanks again for the suggestion re the lux meter.