Originally Posted by whitey_028
you need to find out whats causing the nitrate issue and no xenia does not take out nitrates. There is no documented scientific facts thats say xenia takes out nitrates. On the other hand there is documented scientific facts that clams, shaving brush and mangroves do as they are what filters the oceans. You also may be overfeeding as that is usually the main cause of nitrates in a saltwater aquarium.
Whitey is right you should really look for the cause if nitrates are a problem and you are doing your regular recomended water changes etc. If you are just looking to extend the intervals of changing water than that is a different story. There are more reasons to make water changes than just higher nitrate levels (which you may or may not be aware of). Take a good look at your tank, how many fish, how much and often do you feed them, size of your clean up crew (maybe not enough) and possible places where ditrius and excess food can settle down and rot in your tank. There looks like there is another alternative provided by PURA, it is a filter media that says it eliminates nitrate levels at first and maintains low to undetectable levels for up to 24 cycles (regenerate 24 times with table salt). I have never tried it but am going to buy some to see how if it works. Good luck