This is my first attempt at growing hydroponic tomatoes in my little aerogarden. I made a mistake when first starting this tomatoes and I switched them to a solution of MiracleGro that burned them out pretty good. I switched over to a hydroponic fertilizer but it seems like the plants are just not bouncing back.

The tank only holds 1 Gallon of water and I've been mixing in a lower amount of nutrients hoping to at least give the plants some life back and make sure that the new leaves dont show any sign of burn. Its always the same process. the lowest branch starts to get brown edges and very dry leaves until the whole branch falls off. I have one other plant in there (that i planted after the fertilizer issue) and it is not showing any of the same signs.

Am I maybe still messing up the solution or are the plants simply so
damaged from before that there is no recovery (it happened 1 month ago)? Also I do not own a PPM (I believe that is what its called?) meter but I've been confirming that the ph level is around the right range.

Any advice would be appreciated. Please let me know if the picture is not good enough