Hi. I am growing 4 critical by Royal Queen Seeds in one container. Container is 80l filled with 55l of nutrient solution. 16w airpump, 8 2" airstones. Water temp 20-21C. Started in rockwool. Now it is in pots filled with clay pebbles. Problen is that roots that come out from the bottom of the pot are getting thinner and then just dissapear. They are just normal when they just show, abbout 1mm thick. They dont turn brown, no slimmy stuff. Ph 5.6-6.1. Ec 1.5. Any help welcome.