Magnesium?

Hi there Luke, i have to disagree with Kushgang here, it absolutely does not look like a deficiency it really looks like a lock out. That's because you're already adding nutrients. I'm pretty sure there's both N and P excess. the N excess you can tell by the "too green" aspect of the leafs and the P lockout you can tell by how the leafs are yellowing. Right now you're feeding too much and the tomato nutrients are 4-6-3 , for vegetation you should at 6-3-3 and for flower you should be at 3-6-6 . right now you need to cut back on the nutrients quite a lot. It's a pretty serious problem that will take a long time to fix so be patient, it could take weeks. try watering with plain water a few times before you feed again. Hope this helps ! 🚀