They need nutrients badly. Droop is almost always caused by either too much or too little moisture at the root zone. They look dry to me. If you push in a finger and it's not moist they need water/nutes. You don't need to use smartpots or a humidifier, well, unless maybe you live in the desert. Be sure your containers have drainage holes in the bottom and don't water to runoff if you can help it. Once you have a good well hydrated mix lift up on the pot to gauge the weight. Compare against a dry pot full of mix to determine if they need water or not. With that much aeration (perlite) in your mix its doubtful you have drainage issues; likely the opposite. Try to keep the mix as moist as a damp towel.
Coco & perlite is a hydroponic mix. You need to mix up your nutrients to the proper ppm and adjust ph in range before adding to the plants. Don't cut anything off until they recover. Go look at other growers topping/fim jobs for reference. As a rule of thumb wait at least til the 5th set of nodes before topping and dude...use a blade or something. If you are using nutrients tap water should be fine; no need for RO or distilled.
Ph or EC can be hard to wrap your head around but that are the same thing in different forms of measure. PH has to do with the percentage of hydrogen available to the plants.,,,that's what it stands for: percentage of hydrogen. Plants exchange one molecule of hydrogen for every molecule of nitrogen, potassium, or phosphor or whatever they need. This is a cation exchange. Sounds complex but it means the plant can only absorb what it needs if the correct amount of hydrogen is present. This is the ph range. EC is measured by electric conductivity and is closely related to ph; the same thing just a different way of measuring. In soil the ph is balanced by minerals and/or active raw materials whereas a sterile hydro medium is inert. It has no ph buffers at all so you must adjust ph in range so the plants can absorb all the nutrients you provide.