The brown black root is rot. It's hard to tell about the web stuff, can't really see it good. The net pot your holding doen't look too bad. At this early stage you can fix it. We need much more info. First what is your water temp, very important. Water over 70 degrees is bad, or not enough oxygen in water. Cut the rot off now it won't hurt just set you back a few day. Change your water and use RO or distilled. You need callmag plus to put back what plants need, calcium magnesium. If you don't have it get it. You can use a little epson salts untill you get it. your plants are small so no nutes or very low nutes. The web could be too much water. Lowes or home depot has rainbird products for lawn systems. They have little 1/4 inch cut off valves you can turn the water more or less. Your drip system looks just like mine. I put the cut offs in to slow the water when plants are small only a few bucks for 6. Then turn it up when plants are big and need much more water. Are those peat pots like jiffy7's in the hydrotron rock ? That could be a problem, most peeps cut the sides and wash the plant off in clean water then put just the plant in the hydrotron. I'm rambling cause I can't gow right now, just trying to help. Tell us more. You can tune it in. I had a 6x4x8 room with AC, a dehumidifier, a 1000 watt hotrilux light. 2 five gallon tubs with 6, 3 inch net pots each. Drip sytem, a couple air pumps with 6 inch air stones in each tub, helps cool water and helps water oxy levels. Harvest 3/4 to a pound a month from just six plants. Sea of green, small scale. OK stop me I am rambling. LOL. Tell us more you will get better help , Lots of good peeps here.