Your plants have Bacterial Speck IMO but the treatment for all the leaf diseases is the same - strip off affected foliage ASAP, cease any overhead watering/sprinkling, and spray with fungicides on a regular basis to slow the progression of the disease till you can get a harvest. There is no "cure". And yes there are a number of ORMI approved fungicides available although their benefits are questionable when compared to chemical controls. As already mentioned you can learn much more about all this over on the forum for growing tomatoes here. Dave

I have plenty of leaves that look like that on my lower leaves. As the plant gets older the older leaves get leather and get spots. Chop them off if they bother you that much. You have a problem when the rest of the leaves start to spot and or die. Spray with daconil if spotted wilt or septoria is a prblem in your area.

Septoria can survive on living tissue and plant debris but the odds of survival on metal is slim to none and it cannot create spores below 50 degrees so winter survival would be very limited if any. And since it is air borne any subsequent infections are likely from the air not the cages. But if you want to clean your cages then the standard cleaning solution recommended for disinfecting pots, trays, and other garden equipment is a 1:10bleach solution - 1 part bleach in 10 parts water. Dave

Re: the nutrient issue-- there are folks who post here who grow hydro who may see your post, but I would also ask the hydroponics forum in the meantime. The pale leaves with still-green veins looks like an early nitrogen and/or mag deficiency, but hydroponics is a whole different deal than growing in soil, As for the lesions... It doesn't look like spray damage to me, and it doesn't look much like Septoria. It might be the start of the concentric/target pattern in other diseases like EB or target spot, and botrytis is also a possibility, especially considering the paleness of the lesions. I did spray with a fungacide to kill aphids. Is it possible the fungacide spray caused this? Aphids are not fungus. I guess some fungicides may be somewhat toxic to aphids, and the simple physical action of liquid being sprayed and running off is good at knocking back aphids because it washes them off. A lot of people use just plain water and squirt off the aphids with a vigorous spray. That approach tends to work best outdoors, though, where there are beneficial predators to clean up many of the straggler aphids. If you continue to have aphid problems, you'll need to get something like insecticidal soap to more directly and efficiently address the aphids. Fungicide is an inefficient way to kill insects if it is effective at all. EDIT: if you're using neem, it can work on aphids AND fungus. That said, you apparently needed a fungicide anyway, so it worked out for the best. Are the spots limited to just the leaves in the photo or has it spread to other places on the plant? If only on the leaves in the photo or just a few leaves here and there, I would document well with photos in case you need to refer to them later, prune off the affected foliage, and repeat fungicide application in a week or so. What fungicide are you using?