Veins and Venules: Veins are the large return vessels of the body and act as the blood return counterparts of arteries. Because the arteries, arterioles, and capillaries absorb most of the force of the heartâs contractions, veins and venules are subjected to very low blood pressures.
Wondering when to change your automatic transmission fluid (ATF)? Most manufacturers recommend replacing transmission fluid every 30,000 to 60,000 miles. If you tow, or do mostly city driving with constant changes of gears, it may be wise to change your ATF even more often. Here's why. Your automatic transmission has a lot of moving parts.
Once you determine a schedule that works for you, testing can be done less frequently to confirm your routine is adequate. As a general guideline, you could start with a 20-30% water change once a week. Some people prefer to do a larger change less frequently, such as 40-50% every two weeks. I believe the latter is less desirable since the water chemistry changes more dramatically at once, putting more stress on the fish.