serious issue help a grow brother out.

Ok so im about 2 weeks into flowering and the leaf tips are turning yellow then brown from the tip down towards the branch but only on the tips and theyre crisping upwards? It looks like the bottom leaves get it worse then the top so i dont think the lights are to close . I have a 150w hps about a foot n a half above it so not heat. I have a fan on during lighting hours and its been cooler in there now then it was before the tip problem so im guessing not heat because everything waz fine before. Changes.. ok seeing as its in flowering i upd the nuts as recommended about a week fter flowering also added a nitrogen supp of 3.0.0 so its an aero bucket w airstone in the bottom water on 15 off 15.. so i dont think the cycle needs changed as they were fine before.. theres one gallon of r.o water w nuts. Nutes before were master a and b 1 tsp apeice plus 2 hygrozyme sometimes 3 tsp plus 2 of sweet berry. I added nitrogen supp about two weeks ago at two tsp. I also flush and dump the whole system every weekend to keep it fresh. Ok now the change. I doubled the a and b to two tsp each as recomended for flowering and went to 4 tsp of sweet as rec. Went to four tsp of nitrogen supp as recommended. So today i flushed it out and went with two tsp of nitrogen and three of sweet to see if that helps and two of a and b and three of hygrozyme. So im curious where i went wrong possibly the nitrogen is my guess my other option is adding a half gallon of r.o water to dilute abit so its in a middle of recommended for veg/bloom cuz veg everything was fine. So if i go half gallon itll be less then before but still more then veg. Although the other change was adding the 3.0.0 nitro so since its half itd be.more like 1.5 .0.0? I duno help me out before i fuck a fruity smelling lady up. Also the pistols have been popping up the past week and a few went brown...

Also there is a compact flor light about a foot and a half from the side to a foot i added yesterday for side light but he browning happened before so my guess not that... also ph is a yellow almost green so im guessing between 6.0 and 6.5 so i think i covered all the bases lol...

Nute burn maybe...Whats ppm?

Also pics will turn some heads here and maybe get ya more of a response, um just say'n.

Yeh but my pics dont really show the brown my cam is junk... thats my guess to but im thinkin the nitro did it or just to much nutes in general so i lowered the amount of nitro n the sweet. So im thinkin if that dont help dilute w a half gallon and if that helps up the sweet and nitro to recommended and if it happens again ill kno n ill prolly up the sweet then nitro a week later... i dont have a ppm meter im poor....

It is a link of info from another seed site, but is is a great fully illustrated nutrient problem write up. Lots of good photos. http://www.marijuana-seeds.net/Thanks-ThankYou.htm