Turtles are very messy and produce a lot of waste.
They require a filter that is rated to filter 3x the capacity of the tank.
For hatchlings, we recommend internal filters as canister filters as canister filters:
1. Require a high water depth and hatchlings require lower water levels.
2. They can suck up small turtles, causing them to drown.
For older/bigger turtles, we recommend canister filters.
Water Treatment
We do not recommend any type of additives because 1. They are a waste of money. 2. They contain chemicals that are potentially harmful to your turtle. 3. There are safer ways to make your water safe.
For this we recommend 1. RV filters attached to your hose or python. Or 2. Let your water sit for 24-48 hours with an air stone or small filter. Or 3. Use a sink filter. Or 4. Use bottled water. (spring)
Maintenance
Water changes are to be done weekly. You should remove 25% dirty water and replace it with 25% clean water in addition to any topping off needed throughout the week. You should also do a 50% water change monthly.
For this you can use
Python
Wet Vac
Drill Pump