pH rising too quickly!

im having serious problems with ph rising like wild fire. it raises about a half point every 5-6 hours and im going through alot of pH down. my plants are showing signs of stress and im constantly working so i cant always be around to lower the pH every couple hours. what should i do?

im using aeroponics; watering 15on/15off
nutes = sensigrow 2-part, hygrozyme, b-52
temp = 75F hum.= 50%
lighting = 8 2' T5 HO @ 6500K

is the temerature of your water changing rapidly? water should be room temperature when ph

temp insignificant on ph, what are your res temps? above 70 you probly got some kind of funk growing in yr water. do res change and keep res temps<70