browning tips, almost like drying out

so the tips of the older leaves keep dieing .. slowly, they dry from the edges out, i have been misting, humidity at 70%, 24*c , air is circulated 10 min on, 20 min off, or by temp rise.

im starting to wonder if im underestimating how much water they need. maybe im starving them.. but i also have branches , like undergrowth starting in these little 1 month old plants, no pinching, its odd..

im newer at this.. but how wet shoudl thier soil be, whene i dig my finger down its moist, but no more moist than soil in nature would be if you dug down, thats probably not enough water is it for these fast growing little girls (hoping girls) ?

EDIT: no direct or excesive air flow inside, so not wind drying.

Low PH? Get a soil meter.

ya i might check that, other than that though i may have just plain old been under watering them... i was so afraid of over watering that i might have not been giving them enough... i have increased the waterings. see how that helps.. doesnt seem to have gotten worse over night so heres hoping thats the only issue... on the plus side if i starved them of a little water for a bit and give them enough now the root system should be fairly hardy after that..