What caused this ? Got a few things to give away ...

Hello BigDaddyK, To answer your question its probably your ph. At this stage of flower it needs to be between 5.8 and 5.9 for the first three weeks of flower. The 4th 5th and 6th week 5.7 and 5.8 and the last weeks try to aim between 5.7 and 5.6. Hope this was an helpfull answer. I see your girls are doing better already. Keep on growing my friend. Peace 👍

I agree with mrmunchies, too much nutes too soon, also it looked like you dropped the light a bit too low

For me it lokks like a typical phosphorus deficiency. Under lower PH more phosphor can be taken by the plants, so your ph of 6.5 is a bit too high for an effective resorbtion of phosphor under hydro. About 5.5 to 6.0 should do the job but be aware that many other nutrients could also be absorbed better and could lead to overnutrition.

it's some kind of wierd potassium lock out maybe, the colorful splotchiness is what worries my, probably it's linked to a pH fluctuation. Hope this helps ! 🚀

Looks to me like nutrient burn, your plants are still too young to handle such nutrient levels. I wouldn't use any nutes first week, quarter strength for the next week, half strength for the following week. An EC of 1.5 should be around week 5 earliest, let your plants get strong enough to handle the nutes.

looks to me like your feedingsolution burped out. i dont know how to write in english,,, hahaha... your water in dwc took the wrong way against the gravity and it wetted all the leaves so they look burned

I’m suspecting the silicate, might be too much even at half recommendations from manufacturers.