I've done hours of search through all the old posts, yet nothing conclusive for me. Perhaps some orang lama, lao jiao can help me out here

Thanks in advance.

Scenario:

Have a Custom 6ft x 11in x 11in pond outdoors, intending to afix a internal pump to churn out water into a custom diy filter box sitting on the side of the tank, slightly raised from the pond level.

Clear so far? Hope so.

My aim is to churn the water from the pond, into the bottom of the filter box, going through the media, then let the water overflow in the box back into the pond form the top of the box.

Now here comes the question, tricky or not.

Q2) What should be the flowrate of my pump?
Q2) I know its about 5 times the volume, but per hour or per min (sounds dumb but i'm actually perturbed by this qnz.)
Q3) Will the pump in this case be too powerful for the filterbox causing it to overflow rapidly in all directions instead of the outlet? (imagine a 600l/m pump churning into a 300l container with a outflow of 200l/m. Tsunami Distaster in my own home.)

Thus with this 3 questions pertaining to the scenario above, how fast should my pump be?

Also, if the pump is underwater, the cable will be too short to directly connect to the power point about 5m away. How? If i add extension plug, it will be exposed to the weater, abit unsafe right?
Power cable can't be extended halfway as adviced by an electrician, and the tip of the cable is hidden under a coat to protect the motor when underwater.

How?

Questions questions.. Sigh.
Lol

Thanks for the help guys,

Cheers
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