Water Balancers: To keep your water in balance, you should test the pool several times per week for chlorine and pH levels, and adjust as needed. Test total alkalinity every few weeks or if you have pH troubles, and test calcium hardness and cyanuric acid levels every month. pH Increaser: Granular Soda Ash.
The alveoli are surrounded by tiny blood vessels, called capillaries. The alveoli and capillaries both have very thin walls, which allow the oxygen to pass from the alveoli to the blood. The capillaries then connect to larger blood vessels, called veins, which bring the oxygenated blood from the lungs to the heart.
Movement of oxygen into the blood. Diffusion of oxygen into the blood takes place at the alveoli (air sacs). The air in the alveoli contains a lot of oxygen. The alveoli are very close to capillaries, which are small blood vessels. The blood in the capillaries has very little oxygen and has a lot of carbon dioxide. The walls of both the alveoli and the capillaries are very thin and oxygen and carbon dioxide molecules can move through these walls.