I have a small flood and drain system and everything was fine until yesterday when I decided to replace my nutrient solution. Right now I have tomatoes about 5in. or something out of the rockwool and I seem to have 3 main problems. First, the edges of the leaves curve down a bit, especiall the newest one which seems to have a steep curve. This was a minor problem before, but it seems to have worsened. Second, the edges of the very first (and lowest) 2 leaves seem to be browned on the very end. Lastly, on the new leaves there's some sort of whitish tan near the stems scattered like uneven dots. It seems a bit on the lustery side.

Like I said, I just changed the solution for the first time. The water here in Houston, Texas is very basic/alkaline so I don't know if this is a Ph problem or what. I really don't know what I'm doing so... I don't know what could be wrong. This is my very first horticultural project. Ever.