So here's my answer to your grow question . For the yellowing what you are seeing is a light case of nutrient burn , don't panic its nothing you can't fix my recommendation to you is that you lower they amount of times your plants being fed , not watered but fed with nutrients as well as adjusting the strength of your solution to be a little lower to me its looking like you may have over fed them just a bit . With that being said until your satisfied with how the yellowing stops I would only feed them with PH corrected water . The thing you must understand is that when ever you feed your plants with nutrients they will never uptake it all 100% so some of it stay's in the soil and over time the soil get to be what we know as "hot" thus affecting the root mass leading to nutrient burns . So the best thing to do in order to help prevent this from happening is feed with nutrients every 2nd or 3rd feeding this way you can ensure the soil will never be too hot for your root mass . As for the curling leaves that's classic sign of heat stress you can correct this many different ways , the most cost effective way of course is simply to move the light up or if your plants are raised above ground to lower them closer to the ground . You can also purchase a cool tube reflector combo which essentially uses your exhaust fan to cool your light allowing it to be closer to your plants without the risk of heat stress . I hope the info I've provided you with has helped you on your journey to becoming a grow master ! - Happy Growing!