Help! Yellow spots are bigger! (Pics inside)

I made a thread yesterday about what i thought was heat damage and everyone said my plants looked fine, but today the spots are bigger!

I circled the spots in red.

Please help, i don't know what's going on except that they've drank almost all the water in the reservoir. I have had to top it off with more water. Could they be running low on nutrients since they almost emptied their tanks?

Thanks everyone for helpful feedback.

Here are some closer pictures.

Please help!

It might be light burn, it really isn't that bad though man. Just keep an eye on it. If their is significant yellowing and dying off, then its an issue. Have you sprayed your plants with anything recently? How close are your lights?

It's not that bad... If your giving nutes cut back on how often and it'll be ok