Some tank maintenance today. I went to clean the Gyre and noticed putting it back that it was spinning in reverse. A few months ago I swapped out the extra impeller while others were being cleaned. Reading instructions seems I put the replacement in wrong but cannot figure out what I did wrong. I took off dirty ones to clean and used prior ones. Turned it on and they were spinning in correct direction. My question is are these replacements for when cleaning it or are the different impeller designed to spin in different directions, forwards / reverese?