the difference between photoperiod & autoflowering strains?

hi all, as you can probly guess im a newbie at growing and have spent a few quid on my grow room, I have two 240w blackstar led's with a 180w blackstar inbetween, i have an ebb & flow system with 10 net pots with clay pebbles in it with my seedlings [ 3 weeks old now! ]in rockwool within the clay pebbles.
At the moment i am running on 18/6 & watering twice a day, my seedlings are doing quite well but the lower leaves are showing yellow markings on them,[i will upload pics tomorrow!] i was just wondering what advice people can give me on my setup & which is the best type of seeds & best way to grow either photoperiod or autoflower? also how long to keep feeding the seedlings only twice a day & the best time to put them on full nutes?
I have white widdow x big bud photoperiod seedlings growing this time,

any help is good help thanks

Autoflowers automatically lower, photo plants require a change of light cycles. Auto flowers tend to have a lower yield because you can't control the veg state

Thanks hoonigan, any advice on watering young plants & when is best to change from veg into flowering?

here are a few pics of my setup!

Auto flowers flower according to their age and photos flower according to the light cycle.

Autoflowers are weaker than regular strains because only one of the parents is a true cannabis plant, the other is ruderalis. Autoflowering plants start flowering after about week without the need to change the light timings. This feature is handy when growing outdoors because it means you don't have to wait until autumn for the plants to start flowering. So you can harvest all year round, provided the weather is suitable. When growing indoor I don't see much point with autoflowers because if you want to it too flower quickly you can easily change the lights to 12/12 so regular plants start to flower at the same time as an autoflower.I've never grown using hydroponics but yellow leaves generally means lack of nitrogen. So increase your nitrogen feed concentration until it recovers. Getting the nutrient concentrations right with hydroponics is essential because they cannot get nutrients from anywhere else.

i have only started with just under half nutrients with them being so young so this could be why im short of nitrogen, how would people recommend watering young plants & how often & also how long to veg for under a setup like this for maximum yield? im currently only watering twice a day but im due a water change tomorrow & im thinking about doubling the watering pattern & nutrients?

take it easy with young plants in hydro, id keep the watering the same check your ph constantly and be careful not to burn those little ones. Id veg for 6-8weeks if you have the room.