That pattern is variegation. Whether it is genetic or related to a viral infection, I don't know.
Pick a light schedule and STICK WITH IT or risk stressing the plants into hermaphrotidism.
Is that the schultz liquid? It's the only nute I can think of that's 777. Try to find yourself a better nute. Preferably a cannabis-specific one, but if you can't, the Jacks Classic lineup has a couple that are appropriate; look for approximately 5-2-3 or a similar ratio for veg, and avoid MG and sams choice like the plague they are.
Perlite is preferable to sand next time. It is far lighter and most important, it's INERT and won't interfere with your nutes.