Doesn't have the RO membranes though, those are what are in those 2 canisters that run horizontal on top. Those should last a while, if you bought it used it might be a good idea to replace those as well.
This is the unit you have. The only difference is some one moved the booster pump and added to more stages and another TDS. Id recommend watching this video to understand the operation and features.
What you are referring to is called waste water staging, that unit may or may not be set up that way and its not always ideal. She needs to determine if the two RO membranes are plumbed in series or parallel. It dosnt matter which way they are configured it dosnt effect what kind of membrane you get they would still be the same. but you really only want to series stage when the source water is already on the lower end in TDS. if its between 300-350 or higher you still want to run them in parallel.
What you are referring to is called waste water staging, that unit may or may not be set up that way and its not always ideal. She needs to determine if the two RO membranes are plumbed in series or parallel. It dosnt matter which way they are configured it dosnt effect what kind of membrane you get they would still be the same. but you really only want to series stage when the source water is already on the lower end in TDS. if its between 300-350 or higher you still want to run them in parallel.[/QUOTE]
Having never seen Allyson's RODI system in person I was just trying to help her decipher the filters and their purpose. I defer to your plentiful expertise on the matter, I was just trying to be helpful.