I don't think it's your soil It looks like a fungus of some sort, probably one of the mildews. I'd treat it ASAP with something like Ortho's Garden Disease Control on a weekly or bi-weekly basis until your new growth is clean and healthy. It kills many fungus diseases. And remove-discard the affected leaves to get the spores on them out of the vicinity. I'd also disinfect your wall-o-waters to get rid of the spores, too. Dunk them in a 10% bleach solution.

Although Anney's diagnosis shouldn't be ruled out I'd say you could have any number of conditions in play. Certainly the temperature extremes of poorly maintained WOWs can lead to non-disease damage pictured on certain leaves. Ammonia from the manure or excess salts from other soil additives can also cause wierd effects.

Overall your plants look typical of many plants that have had to endure a few days in WOWs during freezing nights and sunny days. Dropping a remote temperature sensing probe (with min. and max. temperatue memory) in the area of the plants could reveal what these plants are going through. You might be surprised. But as long as you can get them past the cold periods and trim off the damaged foliage you should be ahead of the game.

Because of the high humidity within the WOWs it is always a good idea to also preventatively ward off fungal diseases.

On your other post, you said the daytime temps get to 70F.

Likely the plants are cooking during the daytime. So open the tops of the wall o'water to vent during the heat of day, close late afternoon.

I'm pleasantly surprised that no one has hollered "Roundup" yet :::smile::: as that is the usual refrain following "fungus" :::snort:::