If I'm reading this right you need to back of with nutrient, cool the room or double your run off amount, with coco your run of should be below its original strength.
Yeah I thought getting basically doubling of my ppm and ec looked a little off...
I'm not growing in coco though its soil thats purposefully very low/devoid of added nutrients.
I also noticed I am getting the very tips of the two first proper leaves going funny, like maybe the begginings of burn, I'm guessing even half/two thirds strength mix for a two litre watering is too much and the plant doesn't have the root system to use it up yet.
I think I'll reduce to one third strength for a couple of weeks on the next watering (right now a 2 litre watering lasts about a week before its dried up properly)
Oh and the room is cool already and the temperature in the tent is always in the 70f zone .