Sometimes the airation stones/pumps you get with tank kits or just buy separately are too strong for your delicate fish (like bettas. I know they don't need it, but I like to have it to keep them healthy.) because they create such a strong "current". I have found that you can get stones that have valves that allow you to regulate the amount of bubbles coming out, and they are perfect. When you need a lot of movement, you've got it, and when you have a delicate fish, you can turn it waaay down. You could probably just buy one of those regulating valves to stick in your airline tubing if you cut it somewhere, but I'm not sure.