The present invention relates to a pH buffer box for a water tank that can efficiently utilize space for use in bacteria storage and water tank by managing and adjusting the PH value of the water tank and putting filter media together. In the present invention, in the filter attached to the inner surface of the water tank to filter water, a first inflow channel is formed inside to flow water flowing into a plurality of filter slits formed vertically, and separated into a removable member on the inner surface of the water tank. The housing is attached to a plurality of vertical filters for filtering the floating matter of the water, which is coupled to the plurality of filter slits, and a second inflow passage is formed horizontally so that the filtered water is introduced. A horizontal inlet pipe detachably coupled to a lower portion of the flow path, a filter medium accommodated in the second inlet channel of the horizontal inlet pipe to filter the inflow water, and an outlet opening detachably coupled to discharge the filtered water to the upper portion It is a technical idea to include a vertical discharge pipe which is vertically connected to an upper portion of the horizontal inflow pipe, and a pump connected with a hose to raise water flowing into the lower portion of the vertical discharge pipe and discharge it to the outlet. Therefore, the present invention is configured by combining the vertical filter with the first inflow passage of the housing and receiving the filter medium in the second inflow passage of the horizontal inflow pipe, so that it effectively utilizes space inside the water tank and conveniently stores it to prevent loss. It has a very useful effect that can be prevented.본 고안은 수조의 PH 수치를 관리하고 조절하며 여과재를 같이 넣어서 박테리아 서직과 수조 내에서 공간 활용을 효율적으로 이용할 수 있는 수조용 PH 버퍼박스에 관한 것이다.이러한 본 고안은, 수조의 내면에 부착되어 물을 여과하는 여과기에 있어서, 수직으로 형성된 복수의 필터슬릿으로 유입된 물이 흐르도록 내부에 제1 유입유로가 형성되어 수조의 내면에 탈착부재로 분리가능하게 부착되는 하우징, 상기 복수의 필터슬릿에 각각 결합되어 유입되는 물의 부유물을 필터링하는 복수의 수직필터, 상기
