No, not really. There definitely wasn't before the spray bar. I made the spray bar to disperse the flow a little because my angels didn't like the current. I have mine set up with the intake on one side, the outflow on the other, and a bubble wand under the spraybar and it really makes a nice gentle flow all throughout the tank. You can definitely do ACs if you want to, they are great filters, just have to make sure your water level is up or it will sound like you're sleeping in a rainstorm every night haha. I have a 20g in our bedroom and sometimes the HOB sounds like a waterfall, soothing yes, but not every night haha