Iron Defficiency or Lockout? HELP APPRECIATED!

Hi guys, one of my autos is showing signs of defficiencies and seems to me from reading that it could be an iron defficiency.

The leaves around the new growth and flowering sites are turning yellow, cannot understand why this ones getting a deffiecieny or getting locked out. The others are fine, really strange.

So if it is an iron deff or lockout. It's either calmag or flush with ph'd water to remove salts. But how to I tell what is needed?

Here are a couple of pics, can't really see it that well under the hps, looks alot worse in the flesh and this plant seems to be lagging behind alot.
Help appreciated in advanced will give rep!
Cheers

Rootbound?

try take a pic with your HPS off, new growth usually has a lighter color to it cant really see from your pics tho

If you suspect your growing cannabis plant has a iron deficiency due to too-high pH, flush your system with clean, pH'd water. This will remove any nutrient salts that may be affecting the uptake of iron and help restore pH to the proper levels..

• In soil, iron is best absorbed by the roots in the 6.0 - 7.0 pH range (iron tends to get locked out when the pH is above 7.0, and if you suspect an iron deficieny, you may wan to consider lowering your root pH to ~6.5 just to be safe)

Rootbound seconded.

SnapsProvolone said:

Rootbound seconded.

Click to expand...

Rootbounded must be the problem considering the other plants aren't showing any signs of defficiency. Is it too late now to be transplanting? In 11L square pots atm will use 20s next time.

Cut the bottom out of the pot and set it inside another one that's 3/4 full. Water lightly every day using veg nuts. You should be back on track in a week or two.