Greetings Budboy, Peace and Blessings to you and your loved ones.

The soultions you use in your system are your fertilizer. They are liquified.
Sea salts can be very confusing eg.... kelp, seaweed.

Hydroponics foods need to be accurately applied. One of the things that make soil attractive to many growers is the fact that soil is more forgiving when it comes to making mistakes than its hydroponic opposite...., like over feeding, etc etc.

I would imagine that you started your crop from clone..via mother plant ? or another source of clone? When planst are young with new roots they need to be nurtured. They are very vulnerablle to many things, including salts from your fertlizer. Since many of your plants look like they are well rooted they are most likely out of danger from rotting. The yellowing comes from Lack of N(nitrogen) the brownish spots look like an overuse of P(phosphorus)
I use soil because if you fuck up using hydroponics and make an error, you lose whole crop. Soil is a great barrier. IMO, your plants look burnt and deprived of Nitrogen.

Peace,
dai*ma