Originally Posted by tierodking
what exactly is D I water and how does it help.
my RO system has a deionization cartridge on it already
DI water is water that gone through a DI unit. It is H2O without any ions (minerals).
Simple explaination how it works:
Think of water as a fluid H2O carrying with it small bits metals. Now, think if the DI material as magnets. Pure H2O will just pass through the magnets. However, the metals will be attached to the magnets. So, what comes out of the DI unit is just H2O.
For an aquarium, you want your water without minerals. Minerals are food for algae.