Do you know the brand name of this RO unit? How many GPD can it handle? How big is your tank? IMO I like Air Water Ice RO/DI units, and the unit that I bought was from air water ice and is a 75GPD RO/DI unit. I got my unit for $150 plus shipping I dont remember what shipping was but it was not bad. so google Air water ice and check them out they also have replacement fillters on there site.