Introduction: Freestanding Aquarium Float Sensor

This instructable is devoted to knowing when the water is too low and notifying me. The focus of this is just hardware, no software implementation for now. DISCLAIMER: Measurements are lacking and not precise. It was an idea and I just threw it together :)

I have a saltwater aquarium with these major components:

  • Aquarium
  • Sump
  • Auto Top Off Reservoir

I want to experiment with sensors feeding data to a Raspberry Pi or an Arduino that uses queuing to write to a database along with provide real time (websocket) updates to a web app with their sensor information.

There are existing solutions out there that hang on the side of the tank. I wanted these features:

  • Freestanding
  • Adjustable height
  • Determine if the water was low via a Raspberry Pi and the float sensor

Step 1: Needed Supplies

I didn't have a lot of the supplies, so I had to buy most of it. (Amazon Affiliate link below)

Supplies needed


  • Longer Wire
  • Clamps

Step 2: Acrylic Preparation

The first image is what I got from Lowe's. They cut the left strip and the bottom right strip by 2 inches.

The top right (above the sticker) was used mostly for the stand (wider than 2 inches). I had to use the plastic cutter to achieve this.

The piece that is left (with sticker on top of it) was used to cut triangles out (to support the stand to the base). I was hoping they were pretty good right angles and they were for the most part, the glue can fill in gaps.

I then drilled into the T for the bolt, and then drilled to the right of that for the sensor. Be careful as to not crack the plastic like I did in image 3 and have to cut another piece out.

Image 4 - I then drilled a hole into the long stand to get the proper width. Then I used the Dremel to make a slot the same width as the hole. You can insert the screw and run it up and down the slot to see where you need to shave off more plastic. The Dremel was very effective at cutting into the plastic.

Image 5 - After my broken piece, image 6 is what was left from the 8in x 10in acrylic sheet.

Step 3: Assembly

Unfortunately I do not have much details for this. I had to be creative and have a cardboard box on top of the stand to keep it upright as I glued the triangles to support it.

The images are a few different viewpoints.

Step 4: Done!

I hope to have some companion articles to this, namely software examples and my overall aquarium "IoT" setup.

The image attached is EXTREMELY POOR drafts of what my planning looked like...