I played with filtration a lot, built a mini gravity fed system with Retro BD>vortex>mechanical(brushes>coarse pad>fine pads)>bio media with air>pump chamber>return to pond. Each chamber connected with valve to a waste drain.
Pics I have are a mess and I didn't document it all that well.
But here are some pics.
In 2010.
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Upper pond this year, after 5 year of no filtration or cleaning.
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Here's a schematic of my mini filtration system.
This does not show that there is a drain from the upper vortex to the lower drain system, or the drain valve connections from all the lower chambers.
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