Step 8:

Picture of
Now that we have tested that the unit is holding water without leaking, and the impeller can spin freely it is time to move on. 
In this step we will permanently set the impeller in place so be sure all the waterproofing is done before moving on.

14. Due to the range of epoxies or glues that can be used I will simply state for this step that you should mix your chosen epoxy or ready your glue.  Mine is Super Glue brand 2 part quick-setting epoxy.  I mix equal parts of resin and hardener on a small paper plate and mix with a tooth pick.   Then dab a little on the motor shaft and place the impeller onto the shaft.  Then dab a little more onto the top where the motor shaft meets the impeller.  BE CAREFUL NOT TO USE TOO MUCH EPOXY.  If the epoxy runs over and sticks to part of the motor or lid it will be very hard to remedy it when it is dry.   See image.
Once dry put a dab of hot glue onto the epoxy, just in case the epoxy isn't waterproof.