drop the ph to 6.5.... use something with a high concentration of phosphoric acid, the second number in the fert sequence (N-P-K)... if you want to do it the cheap way use lemon juice or vinegar....... i wouldnt get overly worried about the tips unless it seems to be getting worse fast,, as long as she is getting her fill.... and try to transplant to a bigger pot if you can... make sure to give her a good watering b4 you tranplant,, and be as gentle as possible.... i use peat pots for seedlings so i dont have to transplant,, they will decompose in soil so i just drop them right in... just something to think about for your next time around