Help?

Week 4 of flower and two of my plants in the tent are showing these signs. Any help on what it may be? I water every couple of days, only when soil is dry. I’m running 2 gal pots and use about 1/2 gal per water. Keep my ppm at 1200-1400 going in. Just noticed this in my plants today. Any help would be appreciated. Need to water today so was wondering what to add! I run botanicare line. Silica blast, cal mag, and hydroplex for supplements and cns17 line for nutrients.

Ppms high
Are you using silica and calmag at the full strength listed on the bottle? Everytime you water/feed? You're running ro water I'm assuming?

I see some nute burn. Do you feed every time you water?
Could be salt build up in the soil or your ppms are too high.
I never go above 1000ppm.

I keep my ppm at 1100-1300. I just Aerate my water for a day and ph to 6.2. Never use full amount of nutes and am on a feed, water, water, water schedule. I let fox farm soil do work until week 3, that’s about the time it dropped to 900 so I fed to keep at 1100. I use silica and cal mag every three waters and nutes/supplements every 4. I didn’t think it was nute burn, I though it was potassium deficiency. The other 4 plants beside it don’t have the issue, same genetics. My ppm are never high, that’s really why I’m asking because I crossed nute burn out.