With no explanation, label text_A→text_B with either "not_related" or "related".
text_A: Season 15 of Family Guy ended on September 25th, 2016.
text_B: An aquarium powerhead is a water pump completely submerged into an aquarium to circulate water ; usually this is used to create flow throughout the tank .. aquarium. aquarium. For example a single powerhead could be used at one end of a freshwater aquarium to simulate a laminar river current , or multiple powerheads can be positioned throughout the aquarium to create more turbulent flow .. aquarium. aquarium. A switching or variable-voltage system -LRB- also known as a `` wavemaker '' -RRB- is commonly used in reef aquaria to more closely simulate the movement of ocean water .. Water circulation is vital to proper biological filtration of most saltwater aquaria -LRB- particularly those using the Berlin Method -RRB- , and is useful in freshwater aquaria for allowing free-swimming fish adequate exercise .. Berlin Method. Berlin Method
not_related.