bubbly foam on the reservoir

[chopficaro]

I recently, against someone's advice, added humic + kelp to my NFT system. Just as he said it would, it clogged my roots. So I cleaned the plants roots and replaced channel, pump, hose, and reservoir, and filled it up with 620 ppm of just maxigro + hydroguard. My air temp is 66, res temp is 67.6, humidity at 66, and that's a lot of 6's so i prayed to Satan too. He doesn't seem to be helping though, the old growth that was showing signs of death is continuing to die. The new growth looks OK though, and the roots are pearly white. My real concern is that there is some bubbly foam on the top of the reservoir and the ph seems to be rising to quickly. Give me some feedback plz u guys are really helpful. Thanks!