brown edges on leaves: causes?

PPMN

Who could resist this face??
I noticed a few days ago all of the leaves on my plants have brown edges. What could be the cause? I dose with liquid ferts/iron. Could I be overdosing?
 
What kind of plants?
 
Swords go into a dormant period if you let them. Uproot your sword and check under the roots. If there is an acorn type seed at the base of the plant, you need to cut it off with a pair of scissors. Make sure you do not cut too close to the base of the plant or else it will fall apart. Are you running CO2?
 
my anubias does this... same with my java fern, but theres no rhyzome on the ferns... as i know that will cause the mother leaf to rot.
 
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