What is a level switch

A Level Switch is a device that turns off a circuit when the output voltage reaches a certain value.
In the world of electronics, they are called "level switches." In the world of cannabis, these devices are referred to as "grow lights," "hydro systems," "hose heads," and "trickle trunks."
There are several different types of level switches. Some are more powerful than others, some use electrical current, and some don't even need electricity at all! They each serve a specific purpose, but each type of level-switch does something unique - and some do it better than others.
Electric Current Level Switches
These level switches are used in conjunction with high-powered bulbs like HPS lamps or LEDs. Because they're powered by electricity, they work best with bulbs that have built-in ballasts, like LED's or HPS lamps. These level switches provide the necessary power to turn on the bulb and keep it on. When the incoming power drops below a certain threshold, the bulb shuts off.
The downside about using these bulbs with electric current level switches is that they require a lot of electricity and thus generate a lot of heat. That means the bulb won't last long if your power supply isn't strong enough. Also, bulbs with built-in ballast take up a lot of space and may not fit well in small spaces.
Powerless Level Switches
This type of switch doesn't rely on any kind of power supply. Instead, they use gravity to activate them. Powerless level switches use water pressure instead of electricity and can be used in almost any environment. However, they aren't nearly as good as other options.
They tend to leak water over time, and since they only operate when the liquid is flowing down, you'll never get consistent results. Plus, they're often difficult to install and remove depending on what type of plumbing you have.
Temperature Sensitive Level Switches
Some level switches are sensitive to temperature, meaning that they start working once the temperature goes above a certain point. Since many growers prefer to stay cool under their lights, these switches are perfect for them.
However, they have a big drawback: If the temperature dips too low, the light may stop working altogether. Plus, these switches tend to shut off prematurely, making them less reliable.
To sum it up, electric current level switches work well for lighting LED bulbs, while powerless switches are great for ambient lighting. Temperature sensitive switches are great for both applications.

source of the article: https://adaksepehr.com/shop/level-meter/switches/diapason-and-vibration