Stunted Growth

I have plants in a aeroponic deep water culture system but have noticed that their growth has been severly stunted versus its soil counterparts. The plants are slow to develope new nodes aswell as height, one of them has a dark brown discolorotion on one leave and wilting. This is my first time using this type of method so I was wondering if it could be caused by pH??? I am new so did not get all the tools such as pH reader and adjusters etc.. any suggestions

now then mate i have the same prob, i check my ph every day i try to keep it at 6, but it always seems to be closer to 8 wen i check i didnt have ph down i was using vinegar, i have some phosphoric acid on way in post its mega strong so will last longer, oh ps, i live in hard water area and i use hard water nutes and my ph still is very high so if i was u i wouild get a tester

what temp is the water in your res tank? does it stink? do the roots look healthy and white?

definitely go get a pH tester as soon as possible!