Lees Under Gravel Filter for Fish Bowls

I'm using this Under Gravel Filter for a 1 gallon tubular vase. The diameter of the vase is 5.75" including glass, so this UGF sits perfect at the bottom. I also could squeeze in a Hydor 7.5 watt heater under the UGF because the size matched tight. However, I cut a small notch of plastic from the side of the UGF to run the electric cord of the heater to the vase bottom. The heater runs the temperature pretty high in this little tank, so I am yet to put it on a 15 minute on/off cycle with a timer. Having replaceable carbon media is a great plus to this product. After 2 weeks of using the provided carbon I replaced it with a blend of ammonia neutralizer/carbon blend to give an extra boost to water cleanliness. I opted out of the pretty plastic plant provided with this filter, and placed a live anubias nana attached to a small driftwood. I am pumping air to the UGF via a Tetra 10 Gallon air pump. However, the pump provides more air than the filter needs to operate, so I limited the airflow to the filter via a valve. In the system all I hear is a constant bubbling noise out of the filter's uplift tube(could be bothering) and a very little hum of the air pump which is greatly reduced after placing the pump behind books. My betta is warm and swims in crystal clear water.