Hows your plants doing ? I posted some updated pics in my thread by your request lol. About the yield for the 250watt hps aim for around .5 grams (dry) a watt so if you get 125 grams you will be doing great. That number can go down or up depending on how long the plants veg is, what type of grow your doing (soil,hydro ect) also when in soil the container size will also factor into yield. Also what fertilizers you use will factor into the yeild , as will growing method (fim,lst,scrog,ect ect) lol well just use .5 grams a watt as a rule of thumb and try and hit that mark.