I've been reading a lot about impaction in reptiles. Various articles have suggested alternatives that prevent impaction in reptiles, but they've all been about land reptiles. So far all substrate I know of for turtles carry with them the possibility of impaction.
I do not feed my turtle in the aquarium, however I do sometime drop a carrot peel, which eventually sinks after being soaked. Sometimes I see my turtle scavenging for the carrot near the substrate and I fear that one day it swallows some. Even if their is no food in the tank, my turtle will still search for food.
Is their any specific kind of substrate that is fool proof against impaction? If not then what is the most appropriate substrate for a turtle? And if the risks of impaction are unavoidable then how much is the substrate actually important for turtles?
Update: I removed the substrate completely and put some rocks, as I saw my turtle eating one of the small rocks then spitting it out , I still suspect it might have ate some. I kind of feel it's having a harder time floating, I just hope it didn't and if it did it won't affect it and it'll just be excreted.