Noob grower(please help & tips would be much appreciated)

hey people, just wondering whats happening to my babies leaves on the top, they seem discolored, my big fan leaves below seem healthy as im not sure why!
are they stealing all the good nutes? is it time to cut these fans off !
please help..
Another thing is the reservoir! it is not overly big!! coz of the space!!
should it be bigger or is that ok!

really need help on the color of my babies new growth, from topped plant!
cheers help is much appreciated!

looks like your ph is off. Have you tested it?

with a very small res the ph and ec will swing allover the place, dont use too much nutes, keep it low to start with say < 500ppm, i would get a bigger res, 20-30 ltrs minimum

damn it was 6.8 was 5.5 the other day!! cheers guys!!
imma get me a bigger res!
peace