Yeh my ghost knifes always move my 'furniture' around but they can never uproot my plants. I think you need to slow down on the tren with your knife,

. I've never even had giant yabbies uproot plants, or even giant catfish. But like i said, my plants are geared up on CO2,

, its like test for plants. As long as teh fish is happy and nice and fat,

. Ever threw in a few guppies and goldfish feeders for him to chase around?
All my single tanks have sumps, even my baby nano reef tank to be is 1 foot cube and has a 8" cube sump and a 8" cube refugium underneath its cabinet.