I have two Specs with really long finned VT in each. I pushed some filter foam into the outlet nozzle on one and on the other I tied foam over the nozzle. Both methods slowed the current enough for the fish to swim but the bigger problem I had was the intake grate. When I got my first Spec I watched him when I first turned the filter on. He could swim past it and away from it with no problem but his dorsal fine was pulled in a little and it ripped. The fin has regrown and now I keep the tanks filled so that maybe only an 1/8 - 1/4" of the grate is underwater. I suppose another option would be to place more foam in that section or to prop the supplied foam off the bottom a bit.