Look ma no air! I love it! looking good there Sub. How often are you changing the res.? I have noticed in dwc that if you keep the ppm just right your ph stays stable. I remember the first dwc grows and the ph was all over the place. i was worried about lock out with a high ppm, lol ohhh the things you learn.
its bee a couple of weeks and i have only topped off and checked all the pH and made corrections. im going to be lazy as usual ad only change reservoirs once or as needed (if i see any leaf problems). its all in God's hands til then