I went to go and clean my tank just as the instructions directed, but instead of the filth going out of the tube it mixed with the NEW water. Therefore, I had to change ALL of the water.
(Note: Bettas need at LEAST a 2.5 gallon tank. So, if your betta is in ANYTHING smaller and not happy aka swimming around its most likely because of the tank size.
P.S. If your male betta isn't showing off aka flaring up without seeing itself or another betta he most likely isn't happy nor healthy.)