Reef aquariums are complex and often fragile ecosystems that thrive on stability to succeed. Daily fluctuations in carbon dioxide (CO2) levels in the air caused by normal breathing, pets, and cooking can all impact the aquarium’s pH. The higher the concentration of CO2 the skimmer pulls in, the greater the acidification of the water, often resulting in a drop in pH, unstable dKH, and significantly inhibited coral calcification. Overtime, this could lead to stressed corals’ and even the loss of that coral. For proper development, corals require a stable pH of 8.1-8.4. When the lights are on, photosynthesis is occurring to help stabilize the aquarium’s pH. At night, however, the pH drops as oxygen demand increases. This is especially true during autumn and winter, when windows are often closed and rooms less ventilated. This is the ideal time to begin using the AF Air Scrubber Medium to support a stable reef aquarium. AF Air Scrubber Medium helps preventing harmful fluctuations in parameters caused by low water pH. The medium is a white, dry pellet. It tightly fills the filter chamber, while allowing air flow. As a result, it perfectly absorbs carbon dioxide. Used and replaced regularly, it guarantees stable pH in the aquarium. According to our tests, the AF Air Scrubber Medium can raise the pH ~0.2 – 0.4 degrees and its stabilization in the range of 8.0 – 8.4. We recommend using the AF Air Scrubber Medium together with the AF Air Scrubber filter. This configuration ensures the most effective removal of CO2 from the air drawn in by the skimmer. The color changing medium wears out gradually, easily indicating when to replace the cartridge. We recommend replacing it before the color changes completely. The cartridge is meant for single use, cannot be regenerated and reused. Its saturation with carbon dioxide can be recognized by the pellet color. When the cartridge turns purple it means that it absorbed carbon dioxide. Only original CO2 filter cartridges ensure their uninterrupted operation and the highest efficiency. In order to obtain optimal and long-lasting filtration, it is recommended to use AF Air Scrubber Medium together with a dedicated AF Air Scrubber filter.   Key features Excellent CO2 absorption properties Effectively raises the pH level Supports the condition and growth of corals Prevents pH fluctuations in a saltwater aquarium Indicator of the degree of wear Easy to use The highest quality product, completely safe for fish and corals   Important We recommend replacing media when it changes the color or when your pH levels start to drop One package is a full AF Air Scrubber reactor refill AF Air Scrubber Media can be used together with Carbon If used up media is left inside the reactor too long, it can change color again, but it is no longer effective at removing CO2 from the air When changing out the media, it is best to wear gloves and do it in a well-ventilated space Keep away from children. Product for aquarium use only. Not suitable for human consumption. Keep in a cool, dry place away from direct light.