I would say that the RO
unit is one of the most important parts of a saltwater tank! It just takes the tap water that it is supplied with and runs it through 4+ filters to remove harmful impurities that are found in the water. If you have a 4 stage unit you will get a sediment filter, a carbon block, the ro
membrane, and finally the di
(deionization) media. It works by first forcing water into the sediment filter which removes larger particles that could clog the carbon stage. Then it goes into that carbon block which removes chlorine and other smaller particles that could ruin the membrane. Then the water is forced through a membrane which removes 98% of impurities. Finally it goes through the DI
stage which should take out the left over particles that the membrane couldn't detect. You will need a TDS
meter to measure the amount of total disolved solids that are going out your product line. The meter should read 0 and when it starts to climb it means you need to change out the filters! The RO
membrane will only need to be changed every 6-12 months! Thats pretty much how it works!!!