Hi everyone, I've been reading that a CO2 scrubber helps keep pH up and it improves the way skimmer works. My pH used to drop on a regular until I read that leaving the window open can help keep it up. I've done just that lately but now it's getting cold and thought the CO2 scrubber would be a good alternative to leaving the window open. Also, the only one that I've seen for sale is on premiumaquatics.com (http://premiumaquatics.com/aquatic-supplies/MCU-CO2.html?fe_feedid=126). I read that the chemical that absorbs the CO2 is called sodalime which is a compound formed with sodium hydroxyde (lye) and calcium oxide (quicklime). I found a veterinary website that sells sodalime for $7.50 for a 3lb bag which is way cheaper than buying a $35 dollar replacement cartridge (http://premiumaquatics.com/aquatic-supplies/MCU-CO2-RONLY.html?fe_feedid=126). So I figured I'd make my own by using a common RO filter canister, a refillable cartridge and the sodalime that I found online and just running attaching my skimmer airline from the skimmer to outside with the DIY CO2 scrubber "filtering" the incoming air. Does anybody have any experience with this piece of equipment? Other comments are also welcome..