Rex, I have to respectfully disagree with you on this one. I ran mine on a 75gal tank with great results. I had good enough CO2 levels but I also had good KH levels. I wish I had the before pictures of the tank but I don't. All I have is the after pics. But here's the result of the use of the CarboPlus.Never actually gives you decent CO2 levels on a tank much over 20 gallons.