Aquatic LifeReverse Osmosis 10-Inch Mixed-Bed Color Changing Deionization Resin Filter Cartridge for RO/DI System Units, 3-Pack

This works so well I really can't say enough good about it. A little pricey but it's effective.

I've been keeping reef tanks for over a decade and in that time have learned a lot about water quality. Where I live we have hard water and the quality is rather bad. I also have a whole house water softener and while even being on city water without a softener everything in my home will run red from iron. I know rather sad... you can't expect better quality water from our cities anymore.I realized regular 4.5 pound refill bag was empty a little to late to wait on ordering one as the shipping is rather slow. At that time my TDS meter TDS = Total Dissolved Solids was already showing around 10 and this was the best option I could find on Amazon with quick shipping and price but more expensive than only buying the resign separate from the containers and refilling yourself.This DI-Resin brought my TDS right back to 0 and I've experienced no issues after using it for several months and I'm still using my first replacement filter. The life the product seems to be in along the same lines as the other brand I usually use.Thumbs Up - Great Product

Exactly as listed, fit perfect in my standard RODI setup for my saltwater tank. No issues with packaging or build.

I can’t say for certain what the issue is with the cartridge . While they fit, I kept getting 2-3 tds. Got a refillable cartridge and filled it with the SAME resin and finally getting 0 tds.

We have hard water where we live and if I did not completely dry the car right after washing, it looked like an elephant got too excited all over it.I bought a dual filter container system to provide double the hardness removal. It works PERFECTLY!!! To save your resin, I recommend removing the filter system after the wash and draining the filter containers do they are not sitting in the hard water.I just refilled two of the containers and it was super easy.My only complaint is that when I opened the containers it smelled like tuna fish. It may be from my not draining them after each use.