Liquid circulating apparatus and liquid ejecting apparatus

A liquid circulating apparatus comprising,

• a circulation route configured to circulate liquid through a liquid ejecting head, the circulation route including:
• a supply-side tank leading to a supply port of the liquid ejecting head;
• and
• a discharge-side tank leading to a discharge port of the liquid ejecting head,
• wherein the liquid is circulated by setting pressure in the supply-side tank higher than pressure in the discharge-side tank, and
• a sum of pressure in the supply-side tank and the pressure in the discharge-side tank is set smaller during an entire period of initial filling for completely filling the circulation route and the liquid ejecting head with the liquid than when the liquid is circulated,
• wherein the pressure in the supply-side tank is set smaller during the entire initial filling than when the liquid is circulated, and
• wherein the pressure in the discharge-side tank is set to negative pressure during the entire initial filling.