Black lights are useless,mostly talked about as being good for growing in urban legend type shit or a friend of a friend stuff,keep in mind that if its not mentioned in the grow faq as being usefull for growing to any extent its because its useless.
Watering is a funny thing,its like a video game,hard at first then after a while you casn do it with your eyes closed,listening to what amount of water others give their plants will only get you screwed up,every grow is different & things like plant strain,pot size,soli/medium type,room heat & humidity,available light at dirt level,all these things affect the amount of water & the watering schedule.
Forget about the moisture meter things,you just need to pay close attention to what your plants telling you they need,when the soil looks dry scratch down with your finger about 25% of the way down in the soil,if it still feels dry then you water until a few drips of water comes from the bottom of the pot.
Until you get a feel for how to water your garden properly IMO its better to underwater than it is to overwater,overwatering can screw the root ststem up & can take weeks for the plant to snap back to health,an underwatered plant will normally whip right back into shape within 24 hours of watering.
One other thing about light cycles,the dark period must be uninterupted darkness,you should never introduce light durring a dark cycle & keep it as constant as possible for the length of the cycles,this is where appliance timers are a must to control the cycles.
You can sneak in your room with a flashlight real quick to get something you forgot or to check something real quick but never flip the lights on,not even for a second.