There is a white plastic tube outside the tank. How can I use it?
The black button is to adjust the amount of bubbles at the outlet. If you take it off, you may not get bubbles out of the water outlet. If your pump is big enough, it doesn't matter if you take it off.
The black buckle on the top is an adjustment switch that regulates the intake. Taken off, it is equivalent to the maximum intake.
The white hose should be attached to the outlet of the pump. When the water pump is started, the air can be sucked into the fish tank by the Venturi principle so as to achieve the function of oxygenation. If you do not put it on the water, it will not suck in the air, it can not reach the effect of oxygen.
That hose is outside the fish tank outside the water level, so that bubbles will emerge (that is, bubbles generated in the water and designed). If you put it in the water, you won't get bubbles.
