I'd say they are fried.

Tomato plant food? For Hydro? Was this dried and then you made liguid?

More info would help.

Good Luck

Get nutrients designed for hydroponics. It is some sort of immobile nutrient deficiency because its the new growth.

The fungus on those rockwool cubes is suffocating your seedlings too... Get'em covered up...

you need good nutrients, try General Hydroponics.. once you have roots do 80ml micro - 40ml bloom... thats all you need micro and bloom - run you about 40$ and will last the whole thing. -

also, you should just ditch the hydroton and the rockwool cubes... build a good aero cloner with a rubbermade tote so that your (((roots arent exposed to light))), you can do your entire run in one of these systems... look up DIY aero cloner... once your cuttings have roots you can just drop some air stones in the tote and you have a DWC/Aero hydroponic box- home made for around 55$. (pump & sprayers 30) the rest is a tote and some pvc... super easy bro.. -

no need for all the rockwool and the hydroton as you can tell they are easy places for mold to grow. -

----
if you want to stick with your current setup.. i would do this....

1.do your rooting in the rockwool cubes in a tray on a heat mat... make sure yre cubes are fully rooted before you put them in your system...

2. Duct_Tape and eletric tape or black paint the container that the water is in ( your rez) so that the roots wont be exposed to light.

3. Remove any type of pump you have inside of your water if you have one, you should only be using air stones, hopefully you are...

4. you need way more air circulation in that thing i would imagine, you need air coming IN, and blowing back out... i would have the air come in from the bottom and blow out from the top. ( hot air rises )

5. use FLUORESCENT lighting in that box, or LED lighting, get the blue/red mixed spectrum. - if you want to stay the cheap rout check out the CFL lights at the store, you will need a way to hook these up in your box, they have different connectors at the store you just have to get crafty. - use a single blue CFL until you are ready to flower.. them use the red spectrum.. you will have to research a bit on WHICH CFL lights work the best for different periods of growth... i would recomend getting a short T5 from the growshop and getting some horticulture florescent mixed spectrum.

5. most importantly, if you want any kind of yield out of this style of growing whatsoever... your going to want to do a SCROG - screen of green... you will need to do some research on this, but will allow you to pull a couple ounces out of your small box...

6. stop everything your doing and redo your entire stealth box to match this guys setup----- 150w HPS, DWC, 1 plant, in a mini fridge, + scrog = 4 ounces of top notch.
link: http://www.invalid.com/grow-journals/131013-master-kush-scrog-150w-hps.html

Robeartbrenton has offered some very lucid advice. Allow me, Scrap the hydro setup and get yourself some pots. Those babies are fried crispier than a pork rind in Brownsville.

Want the drunk man said... I agree with!

tomato feed has way way too much Phospherous in it to use in Veg dude. You may get away with it in Flowering but not recommended.

+ ^^^ what he said!

Also Elbarracho has a point, soil and pot culture is alot more forgiving of mistakes. especieally if using non cannabis specific product like Tommy feed.

good luck bro.

p.s the soil in the last pic looks far too wet (unless you just watered before taking the pic)

Peace

Tomato food is for tomatoes...
Your cannabis needs cannabis food.
There are many different brands out there... Choose one. I recommend Botanicare. Pure Blend Pro.

What are the specifics of your setup, i.e. cabinet / room dimensions, lighting, what are the high / low temps? Humidity?

How about the pH of that there tomato food... What's it looking like? Do you check / adjust it?

Tell ya one thing, you should cover your rockwool cubes to get rid of that algae. You should also get tubs that you can't see thru because your res is turning green from algae.

Tell us more so we can help you get it right... We'll get ya in shape over there mang.

Peace