You are sure it's actually spinning backwards, and not an optical illusion based on the tank lights (the same way wagon wheels appear to be going backwards in movies)? At certain speeds, the strobe effect of my lights makes the propellers appear to be going backwards.
Ohh I'm positive. Put my hand in the water and instead of pushing my hand its trying to suck it in and you can feel the water pushing around the outside of the cage.
Ecotech isn't giving away new drysides anymore for this issue, But they are going to sell it to me at half price so that's something.