This Dupla Co2 diffusor is good for up to 60 gallons, has a built in bubble counter and does a fantastic job! We use this for some of our grow tanks. It is very sturdy! Here is Duplas description: The CO2 gas is passed through a fine-porous glass diaphragm and released into the water as a cloud of tiny gas bubbles. The clever physical trick with the atomizer: the gas bubbles are met by surrounding water movement as they rise, thereby releasing CO2 into the water. CO2 is now available to the plants.