I've only been using it a few months. I bought a TDS
meter for like $15 so I can tell when the filters need replacing. Supposed to get 6-9 months out them at least from what I read. I think it has the lifespan of each cartridge listed in the ad on ebay.
180g Reef - 60g Rimless Reef -90G FOWLR- 125g Malawi Cichlids- 40b REEF- 34g Fresh Planted-working on- 20L FOWLR- working on
I have a mix of many different saltwater fish amongst my tanks, but I love my Tangs most of all.