This is my second grow using the same basin for tw...

Hey bmvape!! Its hard to say what could be causing that, but it does seem very possible that with having both root systems in the same basin. That the Healthier plant or quicker root growing plant could very likely "choke" out the other plants roots. Making it harder for that plant to grow well. Are you adding any microbes or anything to help with the root zones? If not i would highly recomend getting a product like HydroGaurd It works great I use it both in my RDWC and my soil grows. also there is another product that is great for hydro called Hygrozyme it helps break down any dead matter so your less likely to get root rot. that one is only used once a week or once ever 2 weeks. but your roots do look great! So that's why it hard to tell what is doing that to the NL. you would see if the roots of the NL are being "choked by the WW roots if they are that is most likely your issue. also add as much oxygen to the water as you can. Happy Growing!!