A Fun Automatic Water Refill Device

Now I'm a senior at Mater Dei high school, Santa Ana, CA. I love to participate in this student challenge now.

We have a small fish tank and grows some tropical fish and water plants in it . The problem arises when we go on vacation as a whole family. Because of the high temperature of tropical fish tanks, （the interior of California is very dry），the water in the tank evaporates very much, and the water level drops rapidly, and eventually the circulatory system cannot work.

I wanted to design a fun automatic water refill device that I could rely on to keep the water level at a fixed position when my family was away for more than a week. (we have an automatic feeder and the fish don't eat much, which is not a problem).

Fusion360

3D printer

a large water bottle

glue gun

1. It works like this:

a large water bottle is filled with water and stands upside down on top of the fish tank. There is a thin tube on the cap that extends below the water level, at that time the water will not enter the fish tank due to atmospheric pressure.

When the water evaporates, the water level drops, and the lower end of the tube gets out of the water level, air passes from the tube into the larger bottle upwords, and the water drops into the tank. The water level rises, and when the water level closes the lower end of the tube again, the dripping stops again, until the next time the water level drops again and replenishing begins.

So water level remains stable.

2. I first found a large bottle of pure water and measured its size. I used Fusion360 to design a new bottle cap with a thin tube that can drip water (note that the bottle cap must be well sealed). I use glue gun to make the good sealing.

3. When I put the bottle full of water upside down on top of the fish tank, I saw that the special bottle cap could complete the automatic replenishment function.But I found it to be very unstable and easy to fall over, especially considering California's frequent earthquakes (overthinking it, haha).So I designed an interesting stand to support this upside down bottle.

4.Installed, and then experimented for a while, my water replenishing device can be guaranteed to run well for almost a month. We plan to use it right now, so that we don't have to take care of our fish tank at all.