Week 4 of flowering leaves browning issue. PICS

Here is what I have going on with my grow:

• GDP flowering about to reach week 4 tomorrow.
• Soil Grow in FFOF/perlite in 3.5 gal pots
• 430 hps with a few cfls in there.
• flora duo a+b (last feed i gave 3.5 ml of A and 7ml of B)
• Just added Grandma's molasses on my last feeding
• Using tap water
• Using ph kit (drops of the green stuff) and trying to keep feeding/watering ph close to 6.5 as possible.
• I feed every other watering at about every 3/4 days depending on moisture/weight of soil.

My problem is that i've just started noticing that my leaves are turning brown on their edges. The pictures are kind of bad but I hope you guys can see what I am talking about.

Any ideas on what the issue might be?

Flush. Looks burnt.

The yellowing is somewhat expected in flowering, the other discoloring looks like maybe an iron or copper deficiency. Just my opinion.

flush them.let it dry out then mix up a quarter strength feed with a little epsom salts( i just gave this advice out less than 5 mins ago to sum1 else). this is always a good routine with loads of probs and although not always garaunteed to fix the issue it won't do any harm.

Flushing them right now. Thanks guys for the responses