I have had one running for about 3 months now and I can't seem to get it to go over 110 drips a minute, it has 300' of tubing the chamber is 4' PVC and it's filled with bio-balls. The water that comes out has 0 nitrates 0 nitrites and 0 ammonia but if I go past the 110 mark I start to get nitrites. At first I only had 100' of tubing so I added more but with 300' now O2 should be out of the water before it gets to the chamber, any ideas.