DavidTheGreatAndPowerful

It would work pretty much how you think it would. Except you need large ph swings to get the carbon to release some of the nutrients. Some people use it in terrestrial plants for that reason. With that being said it would not be a good choice because it would float, it is expensive, and the ph swings would be bad for the fish and plants. A better choice would be Safe t Sorb, turface, or cat litter because they do not float, they are cheap, and they do not need large ph swings to release nutrients for the plants. I have only use Safe t sorb, and it worked great for my tanks they are still running after a few years. You do need to "charge" it first though, and I would recommend waiting about a month before adding fish. I also prefer a small cap on it like an inch or less.