I have a 600 gallon water trough for a snapping turtle. It is filtered using a Skippy filter, which is similar to yours. My filter is powered by a 1hp dirty water sump pump I buy at Harbor Freight for slightly less than $100 (Amazon sells them too). I run it 24/7/365. When it wears out I just...
Shown at the bottom of this page is a list of threads where we've talked about having emergency kits for tortoises. Hopefully you'll find some helpful information in those threads.
Not a good idea to allow him to stay outside at night. Every night I go around to all my tortoise yards and make sure all of the animals are inside their sheds. Then I close the doors so they can't come back out until I open the doors in the morning.
Normally I use the corner of a toe nail clipper, but because of the thickness of that beak, I'd use the Dremel. The sides are too long too. Once you get the top beak situated correctly, then you can worry about the lower beak. . . or you may find it's better than it looks at the moment.