Just got my first sump up and running last week and I noticed today that there is almost no water movement in the sump at the top of the water. I had to stir it up because it was getting bad. What do you guys do to prevent this? I was thinking of a powerhead maybe two so there wouldn't be dead spots. I'm all out of extra powerheads so I thought I would check with you guys before I buy something tomorrow to fix this problem.