First grow yellowing seedlings :( nute problem?

coco... yeah, feed, feed, feed after inital seedling's packed energy is done... cotyledons are your signal (Sorry, but coco is a bit differetn i was thinking soil) you want an ebb and flow of moistore to spur root growth, but also with coco this is a bit different. don't let it dry as much as soil. it holds quite a bit less water, which is beneficial in other ways. as it gets bigger, frequent feedign will be best, if you are there all day long, or have an automated system, but not neccessary to do it that way at all. even with heavier irrigations and longer time between, you don't want the top to completely dry like soil. you can't overwater, and any algea on perlite is surface only -- can't survive without light. can avoid that too. once they get going, i find i have to give a ph-only irrigation every ~3-4 weeks at most with the more sensitive palnts, but i don't gas it on concentrations either.