Gah - some problems last week. As in the photos i started to see some of the older fan leaves on the back left plant start to fade. At first I thought this was light burn, so I put the light up 5 inches. I came back a couple of days ago to find that it had start to spread in less extreme way to the others and that they weren't using any nutes from the reservoir. Further investigation showed that the lines were clogged (because I have been putting Recharge in the res - doh - won't do that again). So I cleaned the res, cleaned the autopot bases, valves and lines. The res is filed with fresh nutes. We will see how it goes.
I think I need to pay more attention to PH also. Will start testing and adjusting daily (as soon as I get a PH pen).