saying that air pumps/bubbles only for decor is so amature.
Are Air Pumps Necessary?
Water with low oxygen content is more common and dangerous to aquarium inhabitants than often realized. Fortunately, the use of air pumps and air stones are an easy and effective way to replenish and maintain healthy oxygen levels.
A constant supply of fresh oxygen allows efficient biological filtration to take place without depleting oxygen fish need to breathe. Aeration devices also promote proper gas exchange and reduce buildup of harmful gasses such as carbon dioxide. They also maintain a stable pH by counteracting the pH-lowering effects of carbon dioxide.
In planted tanks use air pumps at night to provide oxygen to your plants and keep it off during the day so that Co2 does not escape and in turn absorbed by your plants that give off oxygen.
If you have 20 gallon tank get air pump for 10 gallons.
Whisper Air Pumps are the best