Common Mode Noise Filter – Coax Aquarium Heater/Pump RFI Kits Store / Aquarium Heater/Pump RFI Kits Aquarium AC Filter for Heater, Water/Oxygen Pump RFI Aquarium AC Filter for Heater, Water/Oxygen Pump RFI SKU AACF-1.4 $12.95 Buy Now Typical user comment: The filter was quite effective. Was surprised that it actually reduced the noise level more than the signal so S+N/N improved by 1.9 S units. Bill