A small thing can make a big difference. Buy a bubble counter for your beloved fish tank. Why not try thisWYIN W00-02A Single-head Aluminum Alloy & Glass Fish Tank Bubble Counter with Non-return Function Silver? As long as you have it, you can clearly know the volume of carbon-dioxide through the rising air bubbles from the bottom, so as to regulate the carbon-dioxide supply for plants in the fish tank. It has a non-return function to prevent the backflow when the pressure changes. Made of tough material, it is durable for long-term use.
FEATURES
High quality and low price
Small and compact
Easy to install and replace
A non-return function to prevent the backflow when the pressure changes