I only do 20 to 30% water changes once a week. You should test your water regularly to see what the Amonia, Nitrite, and Nitrate levels are so that you know if your changing enough water.
you should do a 50% water change every other week
Change 10% of your water (so 1 gallon of water if you have a 10 gallon tank) per week. Change at least 25% of your water monthly.
How often should you change water pump in a boat
1 gallon. Sugar is soluble in water and should not significantly change the volume
That depends on the number and size of the fish you have added in the tank. But as blanket recommendation you can do 50 percent water change once in a week.
weekly 10 - 20% water changes
That depends on how much water is drawn from the tank and how often it is drawn.
Quite often, as a 5 gallon tank will only suffice for the first few months of a hatchling turtle's life.
you should change it every week so it will always be clean.
1 gallon tanks & smaller need to be changed/cleaned every 5 days.
Every day.
It depends on how hard your water is.