This is a new system still in the cycling phase.
I planted these in January and other then being leggy they looked pretty good at the start.
The first thing I noticed was the original leafs turned yellow but the new leafs were still green.
Now most of the plants have white spots and the leafs are curling up and appear to be dying.
Any ideas on the cause of this?
I have included a picture, sorry for the quality the phone camera is not that good.
Have you given the system a dose of seaweed extract?
What is your pH
What do your other water tests say?
If new growth is coming in nice, then you can pick off the old ugly leaves if you like. If new growth is not coming in...
Well you are not cycled yet if the nitrites are that high. Your pH is high which is probably why the plants are struggling. Perhaps you can collect some rain water or adjust the pH of your top up water for a few days before you use it in the system. Yes a foliar spray of maxicrop would probably be most helpful to the plants, mix according to the label directions or weaker for foliar application but make sure you let the spray dry before the plants will be exposed to bright/hot sun or bright hot grow lights since it could burn the plants otherwise.
What are the ingredients in the pH down? Not all pH down products are the same.
Not sure about the actual ingredients, I purchased it from Aquaponic store on the site here.
"pH Down: Acid formulated using food grade Phosphoric acid. It is plant and fish safe, but very concentrated"
Phosphoric acid is a reasonable choice. There have been some issues with a few of the hydroponic pH down products I've heard of. There was one that had ammonia and citric acid and caused one guy terrible problems so I always recommend reading the labels.
I would say some patience till you get past the nitrite spike before you worry too much. Perhaps start some more seeds while you are waiting.
I had already added some, about 6 gallons or so with PH in the 7.6 range, it didn't change the system PH level any so I will wait until it cycles and see what happens.