**Any ideas on tops yellowing?**Strawberry Diesel (flowering)

Temps stay at 80-82F during the day and 75-80 at night.......humidity is 30-50 depending on how long since I watered.....3rd week of flowering.......using a super soil mix from high times website.....K9 is the base soil and bat guano, casting, perlite, lime, blood meal, bone meal and few others....and then it was left to sit for a month with proper moisture to "cook"...........and I have one 1000watt hps with open hood......and two box fans blowing light head away......with two window units in 10ft10ft grow tent......Runoff is right between 6.5 and 7.5...........and I've been watering with my tap water that tested zero chlorine ph'd down to 7

There are three main causes of yellowing. If it's nitrogen deficiency then you'll see an over all yellowing of the plant. If it's magnesium it will start low. If it's iron it will start at the tops. This is because of the difference between mobile and immobile nutrients.

Another thing to keep in mind is that there a number of things that can prevent nutrients from being available even when present. In your case the iron is definitely present from the blood meal but your ph of 7 is still a little high and probably what's keeping it from being available. Another possibility is that your soil might be rich enough to cause lockout from having to high of an ec.

A lot of micronutrients get locked out with high PH. There's nutrients that absorb at 6.2 ph. Another at 6.5.

In my experience. The run off PH is different from the actual soil PH. I've tested soil that read 6.5 on every test over days. The run off is a solid 6.0 ph. Which IMO is perfect. I swing the ph up during feeding and watering. 6.5-7.0 on run off. It'll drop to 6.0. By that time, I'm swinging it up again to get the range needed.