I bought a cylindrical fish tank with a diameter of 25 cm and a height of 2 1 cm, and an external aerator. I found that the sand hair put into the water made a loud noise. What if it's noisy?

From your description, your external oxygenator is too powerful. If you don't want to spend money, you can add a tee in the appropriate position of the gas pipeline to connect a section of trachea, and use a medical drip control clip or hairpin to control the emptying amount. If the adjustment is good, you can get good results. Santong is a flower, bird, fish and insect market in 0.5 yuan.

As for the filter, it may be troublesome. As far as I know, there is no filter device suitable for your fish tank, but you can modify it with an ordinary filter below 20W (submersible type is better). Simple and practical, but not very beautiful. You only need to work 10 minutes every day. The method is: tie a short flesh-colored stocking at the water outlet of the pump, tie it tightly with a rubber band, and put the pump into the water to work. When raising small fish, you can put stockings on the filter screen of the water inlet and tie them tightly. After work, dirt will adhere to the stockings, just clean them. This can solve the water quality environment of newly hatched small fish, which is very practical.