Posted: Thu May 01, 2008 7:10 pm
Welcome. I don't think the Zeolite is necessary especially if you've got a filter that's appropriate for the tank size (how big is the tank?) with adequate biomedia and a tank that's large enough for the turtles (how big are they?) Ammonia removers work until they become saturated and then start to release ammonia back into the water.
If you think you've got a problem with ammonia, get an ammonia testing kit and test the water.
"You become responsible, forever, for what you have tamed." -Antoine de Saint Exupery-