The utility model relates to a filtering device for an aquarium.The utility model is a water pumping room with a pump installed in the water filtering tank, which can pump water into the aquarium.One or both sides of the pumping chamber are separated by a filter chamber which is communicated at the bottom and can supply water to the family box at the upper end.And the vertical and horizontal intervals in the filter chamber are set.Or filter holes are arranged on the surface with continuous reverse interval and oblique arrangement.And a plurality of filter plates on which filter materials can be contained,A gap is formed between the lowest end of each filter plate and the chamber wall.At the same time, at the lowest end of the filter chamber, a gradually reduced diversion space is formed through the narrow channel of the pump chamber.Through the guidance of each filter plate, the water is filtered in sequence through each layer of filter material.Let most of the water passing through the filter material increase the filtering effect.It also makes it easier for the fine dirt to flow into the narrow channel at the lower end of the gradually shrinking diversion space along the water flow direction.It is flushed into the pumping room and pumped back into the aquarium.Such a cycle；Therefore, it can not only improve the filtering effect,It can also avoid the accumulation of pollutants to produce toxins.Make the nitrification system more stable and durable.一種水族箱的過濾裝置，是一濾水槽內隔設一裝有抽水泵而能將水抽送入水族箱內的抽水室、以及在抽水室的一側或兩側隔設有底部相通且上端可供水族箱之水引入的濾室，且濾室內垂直水平間隔設置、或連續反向間隔斜設表面佈有濾孔、而其上可容置濾材的數個濾板，並令各濾板的最低端與濾室室壁之間形成一縫口，同時在濾室最下方為末端形成一通於抽水室之窄道的漸縮導流空間，進而透過各濾板的導引而使水通過各層濾材依序過濾，讓大部分通過濾材之水的過濾路徑增長而增加濾淨的效果外，且令細碎污穢物也較容易順著水流方向流入漸縮導流空間下端窄道處後，被沖入抽水室內而由抽水泵回打入水族箱內，如此循環不已；故不但可增進濾淨效果、更可避免污穢物沈澱累積產生毒素，讓硝化系統能夠更穩定而持久。
