I have been wondering for some while why manufacturers recommend putting microfiltration at the end of the filtration system in external filters. Does anyone know? Shouldn't the cleanest possible water be passing over the biomax instead of after it?

It could be that if the fine stuff was at the beginning it would get clogged to quickly and cause more frequent need for cleaning. Just my thoughts ...

Yes that was my way of seeing it, but I thought that it would still make sense to put the microfiltration before the biological stage of filtration, since this is supposed to be kept the cleanest, at least that's how I understood it.

i always place my coarse and fine filtration before my biomedia. like you already mentioned it keeps the media cleaner longer. maybe the reason they suggest it the other way is so they can get more revenue from replacement biomedia sales?