I have a 29 gallon planted aquarium hooked up to my split pressurized system. I decided to move the filter-my diffuser-to the middle versus the left hand side where it used to be. Trouble is some of my rotala stems are growing stunted. I put a powerhead aimed at the outflow of the filter to push the water around the tank hoping that it would help, but the issue seems to be getting worse. Any ideas why this is happening and what I can do to fix this issue?