Looks like herbicide injury to me.

Common sources of herbicide:

-drift from spraying weed killer in your yard or your neighbors spraying in their yards

-grass clippings applied to soil from grass treated with herbicide

-mulches, composts, and manures from pastures/trees treated with herbicide

-drift from nearby agricultural spraying of herbicides or spraying on public lands like roadsides, parks, etc. (can travel for miles on the wind), but unlikely here because of how localized the damage is, although air currents can certainly be capricious

-residue in spray bottles/tanks/hoses/nozzles that once held weed killer, then used to spray treatments on plants you don't want to kill

It could also be a virus, but herbicide is more common. BCTV includes curling and purpling, but there's usually pronounced purple veins, and it may not be a problem in your area, wherever you are. You might want to ask your local extension.

It is difficult to know what is wrong since you are using such an unusual approach and unusual products compared to standard practices here. I assume you are in the UK? If you are basically trying to grow hydroponically then I'll suggest posting on the Hydroponics forum here for more help as they may be familiar with your methods and nutrient sources.

From what I can find out about Biobizz Bloom it is a narrow-nutrient spectrum organic really intended only for use in hydroponics vs. Tomorite which is a full spectrum synthetic (I think) fertilizer. So for that reason alone I would expect to see very different results in the plants.

Organics work well ONLY is there is an active soil micro herd of bacteria to pre-digest them. That doesn't normally exist in any sort of container or hydro system. So that may be part of the problem - getting minimal nutrients.

Clearly the plants getting the Tomorite are much better off so I can only suggest putting the Biobizz away and using only the Tomorite.

I'd also strongly suggest you go easy on the citric acid use. It usually isn't required.

I hope this is of some help.

Dave

GB and I were typing at the same time

It's entirely possible you have herbicide injury AND a nutritional problem. If it's herbicide injury, the prognosis is poor. A nutritional problem, OTOH, can usually be corrected.

I doubt it's the herbicide thing, cus the plant is right next to two others that are unaffected. I did use a veg nute in the veg stage for a few feedings. Would too much nitrogen do that? I'm not familiar with signs of toxicity/deficiency in tomatoes. Originally I was just trying to see if a soil/coco/perlite mix made any great difference over cheap growbags, but I got bored at some point and other variables crept in. The other possibility: Since I did it because I'd told my sister that the compost in growbags from Wilko is probably garbage, this may actually be enemy action. She's a big fan of cheap stuff and I wouldn't be surprised if some weedkiller ended up where it shouldnt. There is weedkiller in the greenhouse, but it's only ever used out in the garden. Maybe some blew in, cus this plant was near the door. But...I'm pretty sure nothing near that door would be treated. I'll have to ask on that one.

Haverford West: I doubt it's the herbicide thing, cus the plant is right next to two others that are unaffected.

This is how drift works sometimes. I recently had some drift from my obnoxious neighbor. I managed to cover my tomatoes in time, but some of the other plants got it. In a bed of 9 eggplants, only 2, the ones furthest away from the source of the drift, were affected. In the next bed over of peppers, nothing was affected, even though peppers are also very susceptible to herbicide. But on the bed beyond that one, a few dill plants and a pepper plant showed signs of injury. It's very, very common to see affected plants right next to completely unaffected ones.

It's also very common to have a plant come down with a virus while the surrounding plants don't get sick. Nature doesn't always follow human logic, categories, or boundaries.