Dwc droopy leaves

" ec is fine and ph is fine" sounds like it's totally okay, you got this! okay, you need a bit more humility when doing this. something is wrong. don't assume everything being done is perfect, as things deteriorate around you. assume this is the strawberry banana fast buds diary? it's impossible to get a clear idea without images of teh actual problems. all sorts of things can cause droop from water to lights. i see you have a fce 4800. this is a powerful light on a 12/12 cycle, let alone 150% more hours and DLI for an 18/6 cycle. You only need 66% of the power to reach same DLI. You can very easily give way too much light over 18 hours and 16-20" from canopy if running at 100%. you need to either use it at normal operating distances realtive to coverage and reduce power or raise it higher than normal. and still possibly reduce power. riasing a light will be more wasteful with electricity but it will provide some small increase oflight to the sides and lowers by bouncing off walls at more varied angles. the umol/s on your light's spec sheet are accurate, divide by feet squared of coverage than multiply by 10,764 (if i got that off memory correclty for ft^@ in a m^2) .. this is your PPFd assuming distance from canopy is optimaized for area of coverage, give or take. reference this number with any DLI table - you can google image search to find. if over 40 DLI it's almost certainly this at fault. (with suplemental CO2 at 1300ppm, the threshold is somerhwer in 50's DLI) So without any help and limited info, this is a possiblity you can easiyl rule out. if this is not it it could be a bit too high of nutes causing clawing.

Sounds like the roots are not getting enough air. The plant is drowning. Hard to say without seeing it. Only the tips of the roots should be in the solution. You can prune the roots as it is vegging to have more control over them, and it makes the roots spread out more. While making them more efficient over time. I do this in my dwc grows, and take pictures before, and after pruning each week. Feel free to look. Without more details it is hard to say if this is for sure your issue. Only the root tips need to be in solution.

well u say ec ph is fine .. how about the roots are they white? water temp? tent temp ? humidity? btw will be better if u post some pics