Good roots in coco come with sound watering practices period!!!!!!!! I prefer 100% coco. No need to mix anything like perlite into it. I prefer simple hydroponic nutrients that are easy to use. No additives or 15 different bottles to measure. That kind of stuff only invites problems in my experience so far. Examples of simple easy to use hydroponic nutrients: General Hydroponics Micro and Bloom(6/9 h3ad recipe) General Hydroponics Maxibloom(1 part powder) Hydroponic Research Veg+Bloom(1 part powder and my absolute favorite). Do's: Feed often(At least once a day) Check pH Use a balanced quality base hydroponic nutrient(no organics this is hydro not soil) Don'ts: DO NOT LET YOUR COCO DRY OUT Do not feed plain water Do not add a plethora of additives(they are mostly snake oil anyway so save your $) Never let your coco dry out. Did I say that already? I water at least once a day(except for seedlings at the very beginning). The more I water the better growth and the more roots I get because of the fresh oxygen being pulled into the medium on a regular basis. Dry coco kills roots, and so does wet coco that has stayed wet for too long without irrigation. This is because it has not been fed again to renew the oxygen levels thus causing the roots to suffocate. You just can't "over water" coco. You can only deprive the roots of oxygen. The longer one waits to water in coco the longer the roots are deprived of oxygen. In other words. Feed often and you will get thick and healthy roots. This is a very hard concept for previous soil growers to grasp. In soil you need wet dry cycles because soil holds so much water and so little oxygen at max saturation. Coco is an entirely different beast so think of it as such. I truly believe the KEY is FREQUENT IRRIGATION If you follow these simple guidelines your roots will look better and your nutrient uptake will improve so stop letting your coco dry out. Keeping your coco wet is also a great way to prevent salt build up and salt concentration which in turn obviously leads to healthy roots as well. Here are some examples of plants that have gotten 1-2 feeds a day. Nothing but Veg+Bloom and occasionally +Life(microbial innoculant). That's it nothing else.