Solving the lack of oxygen caused by rising water temperature by making the water surface ripple [Hydroponics].

Have you ever experienced a sudden loss of vigor in your hydroponic vegetables that were growing well until recently?
The reason may be that the temperature of the water circulating in the hydroponics equipment has risen along with the rise in temperature and room temperature, and the amount of oxygen dissolved in the water has decreased.
As the temperature of the water rises, the amount of dissolved oxygen decreases, and if there is a shortage of oxygen, it will cause the roots of the vegetables to rot.
It is possible to increase the amount of dissolved oxygen by lowering the temperature of the circulating water, but it is not very practical (in terms of electricity costs) to lower the water temperature using a cooling system.
In addition, the lack of oxygen could not be solved only by aeration with an air pump, so I would like to increase the amount of dissolved oxygen by using the property of absorbing oxygen from the water surface.

Dead water area occurred under the surface of the tank without a pump, and the water was stagnant.

This is a general view of the indoor hydroponics system at home.
From the water storage tank on the lower left, a pump raises water to the top PVC pipe, and after passing through the second and third PVC pipes, the water reaches the water storage tank and seedling tank on the lower right.
The difference in height between the right and left water storage tanks allows water to circulate through a single pumping pump.

This is a picture of the water storage tank only, but there is a pump at the bottom of the tank in the foreground, so the water in the tank circulates rather well.
The tank in the back does not have a pump, so only the surface of the accumulated water circulates, and the area surrounded by the blue frame is dead water.
A very small amount of water on the surface of the water may be able to absorb oxygen, but the dead water area below the surface, where water cannot circulate, cannot take in enough oxygen.
This area was used as a seedling growing space, but in order to solve the lack of oxygen caused by the rise in room temperature, we will modify the tank in the back.

Water pumped up from the dead water area is dropped to the surface and circulated.

The hose connected to the upper right (PVC pipe) is placed in the tank.
Although the water is not 100% circulating, the water in the area indicated in red tends to stagnate.
Only a small amount of water on the surface was flowing to the left tank, so we installed a pump in the right tank as well to improve the situation.

By installing a pump in the tank on the right, the stagnant water under the water surface was sucked up.
By bringing the sucked up water back to the surface of the water in the same tank, the surface of the water is made to ripple and the amount of oxygen absorbed is increased by increasing the surface area.
As the oxygen-deficient water is brought to the water surface, the amount of oxygen in the entire tank has increased.

In addition, we cut the hose extending from the PVC pipe so that it was above the water surface instead of in the water.
This should make the water surface ripple more violently and absorb oxygen more easily.
I can’t say for sure because I can’t buy a dissolved oxygen meter because it’s too expensive, so I can’t check the numbers.

In the video above, there is no lid on the water storage tank, but I usually put a lid on it because sunlight causes algae to form.
The water hose and the pump that circulates the water are both above the surface of the water, so there is a lot of noise, but I’m willing to turn a blind eye to it.
The lettuce leaves were almost shriveled at one point, but after switching to this method, they seem to be in better condition (maybe).
In the case of root rot caused by rising water temperature, making the water surface ripple may help.