Reef Octopus Universal CO2 ScrubberReduce CO2 in an Aquarium With Reef Octopus Universal CO2 Scrubber The Reef Octopus CO2 Scrubber is a universal reactor that will help control pH levels in a reef tank. The ideal pH level for a reef aquarium should be around 8. 3 for optimal coral growth. If an aquarium suffers from chronically low pH or it is challenging to keep pH within the desired range, connecting a Reef Octopus CO2 Scrubber to the air intake of a protein skimmer is a great