Did you put seals on the ends?

Effectiviness have nothing to do with seals. It has everything to do with principles of working. Blade turbines work by transferring the energy of moving gas/liquid particles to blades via collisions of particles with blades. Tesla turbine have completely different principle - it works because moving particles of gas/liquid transfer its energy via friction with disk in surface layer. And the problem of Tesla turbine is that energy transfer is maximal when gas/liquid flow slowly, without turbulence. As turbulence appear, transfer of kinetic energy become chaotic, particles do not drag disks in one direction, so gas/liquid unable to effectively transfer its kinetic energy to the disks. You have to keep gas/liquid flow slow enough to prevent turbulence. So, if you need something powerful, you need a lot of large disks blowed by slow flows from multiple laminar jets. With blade turbine you just blow on the blades with all power you have and that's fine as soon as blades could sustain pressure and rotation speed. With Tesla turbine, if gas flow come turbulent, efficiency drops significantly, and you can't increase turbine output power just adding more gas/liquid flow, you have to add more disks to turbine.

Also, disks have to be polished as mirror and be very straight, to avoid turbulence creation on the roughness. This make manufacturing Tesla turbine disks a complex task.

So, you have to build a much larger Tesla turbine to have the same efficiency as a bladed one. It is obviously ineffective.