The filter status message must be reset manually. The “Water Filter: Replace” status message can be reset by entering the Settings menu from the home screen. Then, select the Water Filter menu and press the RESET button. This will reset the filter status.
After you change the filter, you must press and hold the RESET WATER FILTER pad until the red light goes off. The light will either disappear or turn green.
Hisoka is one of the most important supporting characters in Hunter x Hunter. He is both a friend and foe of the main characters depending on the situation. Multiple times through out the show he is seen assisting Gon and even saving him.
Yes, in the Hunter Chairman Election arc, it is clear that basically everyone who is a licensed hunter knows that Ging Freecss is Gon's dad, including Hisoka.