Slow grow

How are you watering the plants? Are you getting 20% runoff and watering frequently to keep the coco wet? Coco is a hydroponics medium that holds tons of air so it is critical to keep it wet. I water my plants daily until 20% runoff comes out the bottom of the pot. 6.0ph is within range for coco but is at the very top of the range. Ideally you want every watering to be done at a slightly different ph within the ideal range which is 5.5-6.0. Next watering give a watering at say 5.6 and then the watering after that do 5.8 and then do 6.0 again and then drop back down to 5.5. Watering with varying ph levels opens up different nutrient absorption allowing to plant to eat everything it needs to grow well. Everything else sounds good. Its also entirely possible that this plants genetics just arent the best and is a slow grower or is focusing more on root growth right now. Its possible that over the next week or 2 it could explode with growth once its finished working on its roots. Hope this helps you! If you need any more advice or want to chat about growing, dm me!