Which version of Nitrofska are you using for vegging, and since we're on the subject...which will you use for flowering? (there's four different recipe's on their website)

I live in the desert southwest, and watering daily is mandatory...but feeding with every watering can kill your ladies. If you are not adjusting the ratios so as not to go over the listed weekly totals, you are overnuting.
In other words...if the label says 1 tsp per gallon, once a week...you can go 1/2 tsp per gallon, twice a week. But if you just start giving 1 tsp per gallon twice a week, you are overfertilizing.

Skylights (roof windows?) are usually insufficient for growing cannabis, unless it's a very large skylight that covers the entire room. (it works...sort-of, but is not at all optimal) Also, how are you keeping them on a light schedule? During it's dark period...does it stay dark? (are you interrupting it's dark periods by turning on lights?)

How's your water down there?

Da nada.