Is this normal?

little yellow on new growth isn't necessarily bad. As long as it is vigorous, i wouldn't worry about it too much. you are in coco. that is a soilless medium. You need a "hydro" nutrient system that also contains all your secondary/micronutrients etc.. you provide 100% to the plant at all times. Guaranteed analysis labels on quality products will allow you to calculate PPM of these inidividual nutrients in a precise way with alittle algebra and some googling if you've not had some chemistry classes. Knowing what you put in can greatly reduce effort when things go wrong. Here's a good mix for a ~6.5pH. A different pH will need a slightly different ratio of the nutrients as it impacts their availability in the plant one way or another. N 120-130 P 50 K 200 Ca 100 Mg 80 S 110 if it contains the boron, molybendum and such, those ppm don't need to be calculated in most contexts unless you severely dilute the dosage from instructions. Again, this alo depends on a quality AG brand and not some brand with a cartoon label and crooks re-selling old products with a new marketing and snake oil charm. Tap may impact the last 3 a bit. I have hard water, which likely adds some of each to what is in my mix. My mix is only ~1.3EC not counting tap. You want about 1/4 of that for seedlings/clones for initial fertilization. After that stick to a normal 1.3-1.5EC mix with 10% or more runoff and you'll always have a near-optimal medium for your plants with readily available nutrients in a proper balance. The runoff, if religious about it, will avoid any build up in concentrations. Jack's says 6.5pH, and i trust them over some growers in their basement or their garage with tiny sample size of plants vs professionals doing it for their job and large samples. If your brand says "5.8" i'd go with 5.8 and make small adjustments based on observations of your plant... You can make lots of things "work" but they may not be best... without intentionally referencing our former softcore pornstar first lady malania trump's slogan "be best" bwahaha. if the internode length continues to be very tight, raise light a few inches. It'll grow into the intensity and it'll be a bit before you have to adjust them again, most likely.