Tip-burn is THE classic sign of overfertilization.
To correct, this is the process:
Test the pH of your tap water.
Pour a whole bunch throuch the plant and catch what runs out the bottom.
Test the pH of that.
If it is not in the range 6.4-6.8, you will need to correct it.
Now, how many gallons of dirt do you have?
Take 3x that volume of water, and correct the pH so that it complements the runoff pH- say your runoff is 6.0, you will want to flush with water at 6.8 (the high end). If your runoff is 7.5, you use 6.4 (the low end).
Pour all this water through your plant.
Now, make up a fertilizer solution at 1/2 what teh bottle says to use, and correct the pH to 6.7.
Water lightly with this.
Allow the plant to just chill for a while until it uses up all that extra moisture.
Voila, you now know how to flush an overfertilized plant.

Next question! :jointsmile: