If they are backwards wouldn't the flow just be in the opposite direction? Isn't that what happens when you set the mode to change from forward to backwards? I'll take it apart tomorrow but I still don't see where it's getting air to create so many bubbles.
No. The cage is designed in a way that if the wrong paddle is in the cage it will not push water properly.
The air is being separated out of the water inside the paddles because it's not pulling in water fast enough as the paddles spin.
Here is a way to make sure the paddles are installed correctly.
First look at the cage. The back side it completely sold plastic no grates for water flow. Then there is a thick bar that runs In between the grates. This is the front. The thin bar that runs between the other grates is the bottom of the cage. The grates on the bottom if where the water enters for the paddles and the single set of grates above the thick bar is where the water is pushed out. Notice how the bottom set of grates there is 2 sets and only 1 on the top. This is so the paddles can suck the water in any a higher rate then what it can push out. So that the air doesn't get separated out of the water when the paddles spin.
Now look through the grates and notice the paddle. On the top set of grates u should be able to look through the paddle and see inside the paddle. On the bottom grates u should only see the the paddles long ways. Like this
This is how a proper paddle, cage combo should alway look like.
Now for kicks look inside the cage with no paddle. Inside behind that thick bar u should see a triangle strip that runs down the length of the cage.
That plastic is actually what makes the whole thing work by separating the water out of the paddles. With out that piece the water would just spin with the paddles inside the cage.
Sorry if it seems like I explained it to much but I remember Steve had his upside down and keep saying these pumps suck then I told him it was upside down and he needed to flip it. After he was amazed on how well it worked.