IceCap CO2 ScrubberRaise pH in Your Reef Aquarium with an IceCap CO2 Scrubber The pH in a reef tank should be around 8. 3 for optimal coral growth. If youre struggling to maintain pH or if your aquarium suffers from chronically low pH, connecting an IceCap CO2 scrubber to the air intake of your protein skimmer is a great way to increase and keep your pH level within ideal ranges. Run This Simple Test to See if a CO2 Scrubber Will Help You The Carbon Dioxide (CO2) level