Well, maybe sometimes! If you tend to overfeed your turtle’s consistently, then feeding them outside the tank in a separate container will prevent the extra leftover food from polluting their aquarium, but the problem really is that you overfeed, and that’s not good. If you feed your turtle’s a high-quality pelleted diet (like TropicZone) as recommended, it’s really not necessary to feed the turtle in a separate container. Just remember to feed in small amounts, and only enough for the turtles to eat in 2-3 minutes. Then there should be really no leftover food to pollute the aquarium. The real pollution in the turtle’s aquarium comes from the turtle’s pooping, not eating! If you could get your turtle’s to poop in a separate container, now that would be something!