At that age most likely humidity.give em alittle mist.please don't mist at the end of your light cycle for the day.
If it's miracle grow start over!!! lol, seriously... Soil without timerelease ferts i really don't know how to lower ppm other then flushing it depends how hot the soil is though and how old the plants are if they are to young only thing you can really do is let them grow through it, cause flushing very young plants with enough water to lower ppm would more then likely kill the plant.
Then i don't think you could wash the ppm's down without killing the plant, it would require ALOT of water. I would make sure the ph is perfect both ingoing and runoff and cross your fingers that she make's it throgh the hot spot. Good Luck.
Your good man. The good strong ones should make it but you may loose afew. I did my first grow using mg MoistureControl, i had alot of problems and out of 8 started i ended up with 1 female that was a battle start to finish because of bad soil. On your next grow you'll progress a huge amount if you get some FFOF it's worth it man.
Also i wanna mention ph do you know what your's is? It can cause alot of problems if it's not balenced.
Yeah man id sugjest getting a tester even if it's just the paper strips. Improper Ph can turn your grow from fun to a battle.
You can get them at a pet store or anywhere they have fish/aquarium supplies. Or online if you have the money id get a digital ph meter. You can get a decent one fo like $50. I can send you a link to the one i bought, It's a HM digital ph-80 it's a good deal.