Phosphate readings in RO/DI water-what's to blame?

[dansemacabre]

So, it's time to replace the sediment filter, the 3 different carbon filters, and the DI resin. So my question is, does the DI resin remove Phosphates (I'm getting about 1ppm) from the water, or is that the RO unit? The RO unit, per recommendations of the company, should be replaced every 2-3 years. I was just wondering if it was the DI resin or the RO that needed to be replaced. I'm assuming the DI, but I wanted to check first. Thanks!

 

[quarryshark]

Its the DI resin that removes the PO4. If that doesn't solve the problem, then you may need a new membrane.