The XP3 uses 19W, which is less than 1/3 the power used by the FX5. I'm having trouble finding the media tray specs for the XP3 but it looks like they're close to that of the FX5s. The FX5 does have a bunch of foam surrounding the media trays which gives it a much higher total filter volume, and it does filter at a higher rate.
You would probably be good for a long time with just the XP3. Put pillow stuffing in the bottom tray (the first tray) and something like Matrix, Biomax or Substrate Pro in the other two trays.(my preference is Matrix).
Your water parameters will tell you when it's time to add more.
So I am going to follow your advice here for the xp3 setup. Couple questions though. Where does one find pillow stuffing and why do you use it? I will definitely look into one of those three bio filtration medias. It will likely depend on what I can find in my LFS.
You mentioned using the AC110 for mechanical filtration. What filter media should I end up using for that? I am assuming the media that comes with it is designed for a rounded filtration approach and so will not be the best for mechanical filtration.
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