looking at getting RO/RODI system

[Amadod2]

so im looking at getting a RO or RODI system from BRS it seems they are the cheapest even with shipping, but im not sure what to get, i dont plan on having it running on any switches, i just plan on having it on every so often, so my question is does it really matter if im using an RO or RODI? im just trying to get 0 phosphates in my water,