Suspected Iron deficiency, what provides a good source of iron?

Im currently doing a hempy grow, only 3 plants (LA Confidential/Amnesia Lemon/Blue cheese) I use Monkey juice @800ppm (at the moment) epson salts every so often, Tarrantula micronesia every so often, bat guano, a touch of superthrive and Blackstrap mollases when i flush. Everything has been going fine and they are are flowering up nicely after about 20 days of flower.But....The Amnesia Lemon is starting to become more yellow than the other two. The yellowing has started at the top of the plant, and also the new leaves seem to be allot thinner and waxy if you know what i mean. Im pretty sure its not mg deficiency because i use epson salts, and through reading allot of info im pretty sure its Iron, or possibly zinc deficiency. Whats the best way to treat an Iron deficiency? Also, is there anything else that could be causing this? My wardrobe averages 75-85f and 45-70% humidity. Any suggestions would be much appreciated

Fan leaves generally DO turn yellow during flowering. It's part of the plants life cycle.

Pics of your plants would help us determine whats going on, but in the mean time here's a link that might help you out:

http://www.icmag.com/ic/showthread.php?t=11688

I do believe to much phosphorus locks out iron and zinc.

Is there gardenlime in the mix?If not add some....

molasses has about 20% iron

thanks for the info, im pretty sure its not the natural discolouration that comes with flowering because it has started at the top and is only affecting the top 1/4 of the plant. All lower leaves are fine. Ive only just started the mollases with the flushing which i do every 4th watering so hopefully this should sort it out. Ill report back with some pics soon, thanks again....

mollases seems to have sorted it, theyve gone a darker green again...thanks!