Filter Recomendations?

I currently have Indy and Davy hanging out in their 30 gallon long tank (upgrading when they get bigger but they're happy for now with lots of room to spare!) which I have filled with about five inches of water for them since they hate to be deeper than that and I'm looking for a good filter recommendation for this type of set up. I just tried the Zoo Med 501 but Indy has a habit of pulling down anything and everything that's held on with suction cups (Our turtle islands are not stationary; they are FLOATING). I also just found Indy with his head stuck under the bubble bar and I'm very concerned about him getting caught in there.

This leads me to believe that any external filters that use tubing are not going to be ideal for my boys. Any recommendations for something that would be be slightly better? In the past, I've used Tetra models that seemed to die after a while and didn't deal with the sludge very well, even when I was changing the cartridges every couple of weeks. Therefore...any ideas for a good filter for my two boys? Money isn't really an issue as long as I have something that works; the little monsters have somehow managed to get me to sink most of my paycheck into their care for a couple years now and they love it.

They seem to really love the in tank cliff type of filter that provides a climbing surface but I've found that most of those are not all that great for cleaning out the tank. Any suggestions or ideas for something different?

Thanks!