I recently purchased a smaller 45g co2 kit for my aquariums . After about a month of running out of co2 so rapidly it's not worth the time or money in my opinions . The first - third canister lasted abiut a week and the last one lasted 2 days ... I saw this as a big flaw!... So I just ordered a diy co2 kit knowing I'm going to have to spend a little more time setting up and changing mixture , but also know that it's going to last me once I get it dialed in. And also more cost effective!! In my eyes it's an upgrade for sure . Others might disagree with me but I recommend a diy co2 kit over a small canister co2 kit on a 20 gallon and over!!! Any questions feel free to ask I and others will do out best to honestly answer any questions u may have .