I installed three new grow beds and converted my system to CHOP2. After completing the work I checked my water and my PH went to 7.4 and the nitrates were 60ppm. I cleaned my bio filter and the two older grow beds and the nitrates dropped to 40ppm. PH didn't change. My fish (goldies) still eat everything I put in the tank. I only feed once a day but haven't fed for three days. Plants are doing great but I'm concerned about the PH. Any ideas as to the problem and how to correct it?