If a fermenter is moved from a hot to a cold room, f.ex during cold crashing, the volume of the air in the fermenter will decrease and negative pressure can occur.
This can lead to a phenomena called "Suck-back."
In order to generate equal bubbles, the CO2-channel in Plaato is narrow, making it prone to Suck-back. You can avoid Suck-back by making sure there are no rapid or large temperature changes in your fermentation process.
Alternatively, our Plaato Valve was designed to combat this problem and is included in our Airlock Bundle. You can get more information about the Plaato Valve here: