AK47 4 weeks flowering with yellow leafs showing up and alittle leaf burn / got pic

hey guys. I have a AK47 using techaflora kit for success is sunshine #4 soil. I am using 1 1000 watt Hps and 1 600 watt hps. I am also just starting to use co2 with tank and reg that i run for 15 min a hour. The buds look good and smell great but there seems to be yellow leafs here and there throughout the plant. I have even seen some leaf burn I guess, Not sure what it is but left will just die and dry out around the edges. I water at 5.9-6/0 ph and doing everything I have done before in other grow but in different climites. I have a high temp oh 79/80 and humidity of 35% to 42%. here are my pics from my cell phone. I am going in tomorrow when the light is on and taking more with a better camera. its kinda hard to get the whole plant in one shot if you wanna see the up close leafs.