Black tips on tomato leaves?????

[Farcry305]

Anyone have a clue why leaves look like this its in DWC raft ..I have 3 other tom. in system in rock beds but same system and same water and the others are perfect big beautiful fruit bearing plants.

[Derrick kain]

maybe a calcium deficiency, If its only  in the raft system, then its very possible since the other have replacing nutrients within the medium. You can crush up dried egg shells and place in say a stocking or cheese cloth to see if that will help.

Also what is the water temp?