duechbag cry baby... tips turn yellow some times during flower becasue it neads more nutrients while in flower, you probly have a slight nitrogen deficiency. it's not a big deal. you don't nead to suplement with nutes unless you want. yes you should use superthrive it will help at all stages of your plants life.

and don't be a selfish bitch. you are pissed casue you didn't get help....??? people are doing you a favor to tell you what is wrong they don't have to do it. plus you never mentioned what was wrong with your plant in the post you simpley posted a pic of your plant. it is at an apropriat stage of flower but it's not a very nice looking plant, so instead of saying your plant looks OK they didn't say anyting.