Hardware requirements

Any ESP32 - the platformio file is meant for a nodemcu version but it can be adjusted for any board.

A waterproof ultrasonic sensor with its board: JSN-SR04T

Some people have tried with other ultrasonic sensor which ended up being corroded quickly due to the salty environment.

The board needs to be wired to the ESP32 as such:

JSN-SR04T VCC → ESP32 5V
JSN-SR04T GND → ESP32 GND
JSN-SR04T Trig → ESP32 GPIO5
JSN-SR04T Echo → ESP32 GPIO18

Any support to hold the sensor - note the board + ESP32 should not be put inside the tanks otherwise they will get damaged with the salt.
In my case, I've used an insert in the plastic of my tank in order to screw a 3d printed holder for the sensor, in a way which set it in the middle. A piece of wood with a hole, secured on the tank would also work fine.