Light green streaks on older fan leaves, lucas formula - need help!

Thanks for taking the time to read this, here is my setup

5 gal dwc
pH 5.75 (right now)
ppm just raised it to 585 (0.5 nacl) my pH rises every 12 hours to 5.85 or so and I'll pH down to 5.5 every couple of days. PPM drops 20-30 each day
Lucas formula and some epsom salts (not much 20-30ppm), currently I just add 3ml micro/6ml bloom every day or so trying to find the sweet spot of equilibrium.
res temps are between 60-65F, air is 60-62F at night, 70-72 with lights on

Basically I just switched to flower today, and I'm pretty sure these appeared overnight. Only on 1 plant out of 7, and only on the older fan leaves (2, possibly 3). It also started to taco as you can see. The spots are also kind of dry and they feel thin compared to the leaf




Any help appreciated

i think it looks like really early magnesium deficiency, but the streaks could be indicative of something i'm not familiar with. i'm especially hesistant to say magnesium since you say you give it epsom salt

I haven't given them much epsom since there was no magnesium def for me to treat. I've only given 2 doses, total about 1.25g/5gal. People say you should give 0.5g/gal. It doesn't really look like mag def either, so it's really hard to tell.

Yesterday I added 5ml potassium silicate total ppm 600, pH 5.82. This morning it was 556ppm, 5.92pH. So could it be underfeeding, I'm trying to be very cautious since I stunted them before at 180ppm at 10 days old.