Some grow beds fine others not?

[Wayne]

System has been running for over a year with very few problems. We had a mild winter here, so some plants survived outside. Nitrates did fall off a bit during the coolest months while the fish were not eating. Now half the beds are doing great while the other half look sick. They are all on the same pump with equal flow to each.

I thought maybe it was the type of plants in the beds, but I transplanted a few from the beds that were doing good into the others and they started to look sickly also after a couple days.  Ammonia and nitrites read zero but nitrates are off the chart. Ph 6.8- 7.0

I cut back on the feeding and planted heavy in all the beds. Still no change, so I changed out some of the water. Leaves are yellow in some growbeds with slow growth while nice and green in others. Any Ideas why some beds can grow so well while the others don't?

All beds were cleaned at the same time! 

[TCLynx]

What kind of system?  Raft?  Media?

What is the media?

Have you dosed with any seaweed extract?  Chelated Iron?  Those two thins can sometimes help where plants are showing signs of deficiency.

If it's a raft system, are all the airstones operating at peak?  Clogged air stones will certainly give you dismal growth and poor nutrient uptake.

If it's flood and drain with siphons, make sure all siphons and gravel guards are in good order.  A clogged bed might give poor growth.  Or a siphon caught in constant flood or constant drain will leave plants in different states.

How is the lighting?  If some beds are getting better sun than others, they will have different growth.