Hi and welcome to the forum
What sort of turtles do you have and how big are they?
How big are their aquariums (length x width x height)?
What sort of filter is on the tank?
How often and how do you clean the filter?
Are there any other occupants in the turtle tanks besides the turtles?
How often do you do water changes and how much do you change?
What do you feed them and how often do you feed them?