Help!!! Strange burn on some of my plants leaves

[MrCantSpellGood]

Hello Good People

I am having an issue with two or three of my plants which leaves are getting these strange burns. Two of the plants are getting affected really badly which is affecting their growth rates clearly. This while the mass majority of my plants are unaffected and have no burns besides these two or three plants. Please check out the photos for images of the burns.

Just some quick information about my grow for context:
- First grow
- 16 plants grow with circulating DWC
- Just started week three of veg
- I was having some water temp issues with the temp being too high with it sitting around 24c but that has come under control now
- No HP issues with HP sitting at about 5.7
- Using General hydroponics nurts
- Running under Kingled 4000w quantum boards

Please any help would be greatly appreciated

 

[Tersky]

Looks like caclium deficiency and ph issue. 5.7 is too low for calcium to be absorbed by plant so it may just be a ph issue unless you are using distilled/RO water in which case i would add cal mag. Get your ph to 6.0 first. Check out hydro ph absorption chart