What do you guys think here

This is a northern lights auto under a mars hydro tsw2000. Usually 70-80 degrees, 40-50 RH. Fox farms happy frog with fox farm nutrients. I think my pH meter was miscalibrated for a bit so was probably watering under 6.0ph but got that fixed. I have these brown curling leaves all over the place (top and bottom). Measured 60k lumens, ppm of runoff after a recent flush was 500ppm, 6.2ph. I'm not really sure what I'm looking at here as the plant looks otherwise healthy (top of stems have purple lines, but it was LST'd and my lights were a little close, I raised them after measuring 90k lumens). First indoor grow measuring nutrients and pH, I combed all the "plant issue" articles and threads but couldn't really find anything that matched. I guess could be lockout from the low pH but I flushed a bunch and it seems to be continuing.

Thanks in advance! I have everything set up in a 4x4 to do cocoforcannabis auto-watering and auto-draining setup so I'll prob start a journal once this run is done. I've lurked forever and got a ton of good advice, this place is great!

Phosphorus deficiency. Your pH is too acidic for bloom, 6.5 to 6.8 is good.

Thank you! I did find some pictures online that were steering me in that direction, wasn't sure though. Appreciate it