Light cycle and snails

I recently put my lights on timers due to my retail work schedule; I feel the little buggers could use some consistency under my supervision. How long do the lights need to be on for? I don't have any fancy T5 or MH lights yet just basic run of the mill white n blue lights (saving for the fancy stuff) Is there a set amount of hours (say twelve) and you just split it (say eight white, four blue)?

Also I noticed one and a couple other of my Astrea snail shells are starting to look chalky. At least I think that's the best way to describe it. Possibly not enough calcium? Any thoughts?

 

are you using PC lamps then Rulu?

how many white ones and how many blue ones?

I would run the blue ones for 12 hours total - coming on 1 hour before and then going off 1 hour after the others , to give dawn and dusk type setting for tank

run the white lamps for 10 hours total

Steve