Help if you can...

[Bluey]

You do have a very high VPD for that stage of growth. Soil is probably far from ideal given your lights and environment.

When I grew outdoors in soil I would water once or twice per week, unless it was quite hot/windy.

If I grew in pots they were 3 times that size. Soil needs mass and bulk to function properly. Run off in soil grows flushes nitrates from the soil which is a loss of not just N but all forms of nitrates.

I dont think I can nail any one issue here.

 

[Allenpro]

Isnt Sledge Hammer a flushing agent? I dont grow in soil but I wouldnt use that or anything similar in hydro until they are done. It kills the bacteria culture as well as flushing out the nutrients. If you have only fed Cal/mag recently I wouldnt think its a toxicity issue but again I am a hydro grower and for soil that may be bro science