im working on possibly buying a 280.........i have one xp3 and it says it will filter a 175......the xp4 says it will filter a 260......so my question is if my xp3 with an xp4 would filter a 280?
Those are manufacturer recommendations, Alot will have to do with the type and number of fish you have. You can also improve the xp3/xp4 by using some prefilter ceramic rings in the first basket, then a course sponge. Then in the second basket go with eheims Ehfisubstrat or Ehfisubstrat Pro. I would imagine though the combo of xp3 and xp4 should be fine.
Those are manufacturer recommendations, Alot will have to do with the type and number of fish you have. You can also improve the xp3/xp4 by using some prefilter ceramic rings in the first basket, then a course sponge. Then in the second basket go with eheims Ehfisubstrat or Ehfisubstrat Pro. I would imagine though the combo of xp3 and xp4 should be fine.