[me12]

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?

 

[Terrainosaur]

Do you mean at the intake? That part I understand, to prevent fry from getting sucked up. But if you mean after the Bio filter, that would be weird.

 

[herefishy]

The reason for "filtering down" is simple. A good filtration system removes particulates large first, smaller, then smallest. This prevents each stage from becoming clogged and therefore ineffective. Multistage filtration is the best way to go as you can see. The smallest of particulate matter is the last to be filtered thus keeping each "stage" free of excess debris.