First DWC/LED Tomatoes

[forma]

So I have these baby tomatoes and I'm wondering what is going on, this is my first time growing them in DWC with 600W LED's. I changed the water our yesterday and couple seem to have very hard and britle leaves. There is purple on the stems and under the leaves. I am currently using Maxibloom, hydroguard, and CalMag in each. The ph stays around 6 in each bucket and temps are always 70 inside the tent. I was told by someone to not worry about TDS/PPM when doing NUTS, that I should just use the recommended dosage on the Maxibloom. It calls for 1-2 teaspoons per gallon so I've been starting them off at 1 teaspoon and I checked the TDS/PPM and it is like 145. I know tomatoes call for like 600-1000, but I would literally have to use 10x the recommended amount to get to this number. I am curious should I be doing that or just doing recommended dose. I use reverse osmosis water in the DWC also if that helps. The roots look fine and long, I just have concerns of how I should be handling the nurtients going by TDS or using recommended dosage and why do I have so much purple under the leaves and the stems, also why would they be britle and hardening leaves. I know this is my first post and I appreciate any information that can be thrown at me. I attached a few pictures if that helps and I can add different shots and more info if it's needed.