May help to get em off the floor. Water thoroughly until you see runoff then let em dry. If you don't water thoroughly you get dry spots and roots don't like that. Water with
calmag only if using RO if they are over fed. I would say 600ppm all in bit never go by numbers they just let us see a picture of what's going on and are guidelines... Go by the plants. Natural light photos would go a long way. Personally I think getting them off the floor will improve root temps and increase uptake rates and overall growth. My soil sits about 79f with lights on. Uneven watering may have cause some (idk what to call it) hard spots??? So next water saturate well and make sure the water is room temp. Beneficials are always a plus.
Humidity is low if you can bump it up to 50-60% it will take some of the stress off the root system which imo is the issue. Not the humidity but overall root stress, lack of o2 high demand and uneven soil moisture.
Just my thoughts