[grinling]

add epsom to your feeder

[Lardman]

I'll give them a spray but it doesn't feel like that to me.    The pictures aren't the best, it start with black legions on the underside of the leaves.

[grinling]

highly rec Dr Hessayon veg book...supermarkets/library...has piccys

[Goosegirl]

Curly leaves caused by temperature variation have always shown on the top leaves of mine - not seen it before on lower leaves.
There's always a first time though 

That's funny - I've always seen it on the lower leaves where they curl inwards and up whereas the upper leaves curl outwards and down.

[Lardman]

Quick update on this.

Although the plants look pretty ram-shackled they're still alive. Must have been magnesium then    It came on so quickly though, and I've only fed them once with comfrey tea at the same rate Id fed the top GH (100ml/ 10L watering can) wondering now if that was too rich ?

[Goosegirl]

I know that over-feeding can lock up some lesser nutrients so it may have been the reason. Glad they are picking up now.