PROBLEM TO BE SOLVED: To provide a non-hermetic water tank substantially preventing the lowering of water level concomitant with blowing air into the water therein.SOLUTION: The non-hermetic water tank comprises a water tank body and an air-blowing means functioning to suck air of relative humidity 60% or higher and blow the air into the water in the water tank body. In this non-hermetic water tank, it is preferable that the above water tank body have a non-hermetic lid, and the above air-blowing means comprise an air-sucking/exhaust pump, an air-sucking pipe having one end via which air between the water level in the water tank body and its lid is sucked and the other end connected to the pump, and an air-blowing pipe having one end connected to the pump and the other end via which air is blown into the water in the water tank body.COPYRIGHT: (C)2009,JPO&INPIT【課題】空気を水槽内の水に吹き込むことに伴う水面高さの低下を実質的に防止した非密閉型水槽を提供すること。【解決手段】水槽本体、及び、相対湿度60%以上の空気を吸い込んでこの空気を水槽本体内の水に吹き込む空気吹き込み手段を備えることを特徴とする非密閉型水槽、好ましくは、前記水槽本体が非密閉型蓋を有し、前記空気吹き込み手段が、空気吸排ポンプ、水槽本体内の水面と前記蓋の間にある空気を吸い込む一端と上記ポンプに接続された他端を有する空気吸い込み管、及び、上記ポンプに接続された一端と水槽本体内の水に空気を吹き込むための他端を有する空気吹き込み管を備えた上記の非密閉型水槽。【選択図】図1
