Transcript of Heart Disease and the Excretory System. Heart Disease and the excretory Heart disease slows the oxygen flowing throughout the body. So oxygen moves slower to the excretory system.
The most likely causes of a shift in pH are: 1  Something in the water source buffering the water. 2  Something in the tank buffering the water. 3  or Something you are adding to the tank.
If pH consistently decreases, something in the aquarium must be releasing acid, or it may even be in the tap water. It's easy to check the pH of your water supply and see if any decoration or substrate material is not intended specifically for aquarium use.