Just wanted to add my way of cutting the slot as I've not seen it mentioned:

Basically I take a standard piece of 1"/25mm aquarium safe plumbing tube a 1"/25mm end cap and 1"/25mm 90 degree bend or connecting bush.

Determine how long the tube needs to be, adding on enough overhang for an end cap at one end and a 90 degree bend (or connecting bush or whatever at the other).
Get a hacksaw blade and make 2 parrallel cuts the whole length of the pipe 3mm apart.
Once cut the pipe will seem slightly smaller in diameter and lose some rigidity
Get some solvent weld and apply to the pipe to stick on the end cap and a 90 degree bend (or connecting bush or whatever at the other), ensuring as far as possible the tube isnt compressed.
Wait 30 minutes and rinse in water.
Pipe rigidity increases and you can connect up to pump
Any fine tuning of the slot can be done with a sharp stanley knife, but obviously be very careful with fingers etc!

This means no requirement for power tools but does require solvent weld and a couple of reef safe plumbing part costing pennies (or cents I should say!).

Hope this is of some use to someone.

Steve