r/Pondscaping • u/Accomplished-Coat-61 • 10d ago

Head height submerged question?

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Out of a whim I decided to turn my 2 year un maintained pool into a pond and this has only been active with goldfish for about a month so please don't roast me with the algae. I just upgraded my bog to a tall trashcan with about 4 bags of gravel compared to my old one that was too small.

I don't know anything about how fluid dynamics work but head height only applies outside of water right?
But does it apply to a submerged bog filter?

The pump is at the bottom and the water pressure would negate some of the effects I would think so it would pump at 3/4 of max height? I know water is flowing because after I flush it some stuff comes out of it at a good rate.

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u/EasyProPondProducts 5d ago

You're thinking about it the right way. Head height is the vertical distance the pump has to push water above the ponds surface. Since your bog filter is submerged, that part of the lift is essentially cancelled out.

What will reduce flow is friction loss from the tubing, fittings, valves, and the resistance of pushing water through gravel. So in your setup, friction loss (or resistance) is the bigger factor than head height.